AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 817 PM MDT SUN AUG 15 2004 .DISCUSSION...COMPOSITE RADAR TRENDS AND RUC INDICATE THAT WESTERN NEBRASKA CONVECTION WILL GRADUALLY MOVE SOUTHEAST ACROSS PORTIONS OF THE FORECAST AREA. CONSEQUENTLY HAVE UPDATED GRIDS AND ZONES TO INCLUDE SLIGHT CHANCE POPS FOR SHOWERS AND THUNDERSTORMS OVERNIGHT. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ FS ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 345 PM EDT SUN AUG 15 2004 .DISCUSSION... MAIN FCST CONCERN IS PCPN POTENTIAL MON-WED. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW PERSISTENT STRONG WRN NAMERICA RIDGE AND ERN TROF. RIDGE HAS STRENGTHENED NW THRU ALASKA...AND THIS IS SENDING 2 STRONG SHORTWAVES INTO NW CANADA. FIRST IS HEADING THRU THE NW TERRITORIES TOWARD HUDSON BAY AND THE SECOND IS DROPPING S TOWARD THE NW TERRITORIES. THESE 2 SYSTEMS WILL LEAD TO THE DEVELOPMENT OF A LARGE...DEEP UNAUGUST-LIKE POLAR VORTEX IN THE VCNTY OF HUDSON BAY BY THE MIDDLE OF THE WEEK. FLOW OVER THE UPPER GREAT LAKES WILL BECOME DOMINATED BY THE VORTEX. IN THE MEANTIME...OF MORE IMMEDIATE INTEREST IS A VIGOROUS SHORTWAVE DROPPING SE TOWARD ND. AN AREA OF SHRA/TSRA HAS BEEN OCCURRING AHEAD OF SHORTWAVE WITH PCPN NOW INTO NRN ND/NW MN. MODELS ARE IN GOOD AGREEMENT TAKING SHORTWAVE TO CNTRL MN BY 12Z MON AND THEN TO LAKE MI BY 12Z TUE. AS IN PREVIOUS RUNS...BEST DEEP LAYER QVECTOR CONVERGENCE AND 850MB THETA-E ADVECTION PASS JUST S OF HERE. SO EXPECT BEST OPPORTUNITY OF SHRA/TSRA TO BE JUST S OF UPPER MI AS WELL. TONIGHT...SOME WEAK FORCING DOES SPREAD INTO THE WRN FCST AREA OVERNIGHT. HOWEVER...THERE IS ACTUALLY WEAK NEGATIVE 850MB THETA-E ADVECTION UNTIL LATE TONIGHT WHEN POSITIVE ADVECTION BEGINS. IN ADDITION...ETA FCST SOUNDINGS APPEAR TO MAINTAIN SUFFICIENT DRY AIR OVER THE WRN FCST AREA TO KEEP PCPN MENTION OUT OF FCST. MOISTURE GRADIENT IS TIGHT THOUGH...SO EVENING SHIFT WILL NEED TO MONITOR PROGRESS OF SHRA UPSTREAM. MON INTO EARLY TUE...THETA-E RIDGE SPREADS INTO W AND CNTRL UPPER MI...REACHING E MON NIGHT. HOWEVER...AT THE SAME TIME...SHORTWAVE AND FORCING WEAKEN AS HAS BEEN INDICATED FOR SEVERAL MODEL RUNS. TSRA POTENTIAL APPEARS MINIMAL AS ETA/GFS KEEP LIFTED INDEX AND SHOWALTER INDEX POSITIVE...AND MIDLEVEL LAPSE RATES ARE NOT STEEP (LESS THAN 6C/KM). ETA BARELY SHOWS ANY 0-1KM MLCAPE (AROUND 100J/KG) WHILE GFS SHOWS NONE. ALL THIS ARGUES FOR MAINTAINING CHC RANGE POPS FOR THIS SYSTEM. WILL BUMP UP POPS TO 50 NEAR WI BORDER MON GIVEN CLOSER PROXIMITY TO BETTER FORCING AND GIVEN SHRA COVERAGE UPSTREAM TODAY WITH SHORTWAVE. OTHERWISE 30-40 POPS WILL SUFFICE... LOWEST ACROSS THE N AND E. HAVE MAINTAINED DRY FCST OVER THE E UNTIL MON EVENING. WEAK BOUNDARY JUST ABOUT WASHES OUT AS IT MOVES ACROSS AREA ON TUE. WITH WEAKENING GRADIENT...LAKE BREEZES WILL DEVELOP DURING THE AFTN. LIGHT WRLY GRADIENT FLOW WILL FAVOR ENHANCED CONVERGENCE DEVELOPING OVER ERN FCST AREA AS LAKE BREEZES FROM MICHIGAN AND SUPERIOR HEAD INLAND. ETA SHOWS SBCAPE INCREASING TO AROUND 1000J/KG FOR A REASONABLE SFC T/TD OF LOW 70S/LOW 60S WITH PARCEL ABLE TO PASS LAYER OF DEVELOPING MID LEVEL WARMING. SOME CONCERN ABOUT DRYING IN THE MIDLEVELS...BUT KINDEX STILL UP AROUND 30. WILL ADD MENTION OF AFTN SHRA/TSRA OVER ERN FCST AREA DUE TO FAVORABLE CONVERGENCE AND AVBL INSTABILITY. TREND OF FASTER SPEED WITH MIDWEEK COLD FRONT THAT STARTED WITH 12Z/14 GFS HAS BECOME BETTER AGREED UPON BY THE MODELS. ETA IS A GOOD 6HRS FASTER WITH FROPA. PREFER CONSISTENCY OF RECENT GFS RUNS WHICH ARE SUPPORTED BY UKMET AND CANADIAN. THIS LEADS TO FROPA DURING HEAT OF THE DAY WED. EXPECT ONLY A RELATIVELY NARROW BAND OF SHRA/TSRA TO ACCOMPANY FRONT WITH DECENT LOW-LEVEL FORCING BUT GENERALLY WEAK MIDLEVEL FORCING AND UNFAVORABLE RIGHT EXIT REGION OF UPPER JET PASSING OVERHEAD. DEPENDING ON EXACT TIMING OF FRONT AND CLOUD COVER (WHICH LOOKS FAIRLY MINIMAL AHEAD OF SHRA)...TEMPS COULD BE QUITE WARM WED WITH FCST AREA UNDERNEATH 850MB THERMAL RIDGE (+14C) JUST AHEAD OF FRONT. BELIEVE TEMPS AROUND 80 NOT OUT OF THE QUESTION ESPECIALLY CNTRL...BUT WILL STAY A FEW DEGREES BELOW THAT FOR NOW GIVEN UNCERTAINTY ON FROPA TIMING/CLOUD COVER. THU-SUN...GFS/ECMWF/CANADIAN/UKMET STILL SHOW DEEP POLAR VORTEX AND ANOMALOUS LOW HEIGHTS FOR AUG IN THE VCNTY OF HUDSON BAY DURING THIS PERIOD AS STRONG RIDGES REMAIN OVER WRN NAMERICA AND N THRU GREENLAND. TEMPS WILL BE TRICKY SINCE FCST AREA WILL BE ON S EDGE OF VERY CHILLY AIRMASS ASSOCIATED WITH VORTEX. ANY SHORTWAVES ROTATING THRU BROAD CYCLONIC FLOW WOULD BRING BRIEF WARMING FOLLOWED BY A SHOT OF COLD AIR INTO THE AREA. AT THIS POINT...WILL TAKE A CONSERVATIVE APPROACH TO TEMPS WITH READINGS BELOW NORMAL...BUT NOT SIGNIFICANTLY. WILL NO DOUBT SEE FURTHER FLUCTUATIONS IN TEMPS IN COMING MODEL RUNS AS MODELS VARY PLACEMENT/DEPTH OF POLAR VORTEX. AS FOR PCPN...THERE IS THE SMALL POSSIBILITY OF A FEW LAKE EFFECT SHRA EARLY THU IF ONE BELIEVES THE STRENGTH OF COOLING SHOWN BY GFS (850MB TEMPS AROUND 0C). DEGREE OF COOLING MAY BE OVERDONE THOUGH PER OTHER MODELS AND GFS ENSEMBLE MEAN SO HAVE NOT INCLUDED POTENTIAL IN FCST. OTHERWISE...PCPN FCST WILL BE A PROBLEM WITH UNCERTAIN TIMING/LOCATION OF SHORTWAVES ROTATING THRU CYCLONIC FLOW AND POTENTIAL FOR AFTN SHRA WITH DAYTIME HEATING AND COLD AIR ALOFT. MODELS SUGGEST A SHORTWAVE ROTATING THRU THE AREA AT SOME POINT LATER THU OR FRI...ESPECIALLY ECMWF/GFS WHICH SHOW A MORE PRONOUNCED WAVE. WILL ONLY INTRODUCE SMALL CHC POPS ON FRI WITH LITTLE CONFIDENCE IN TIMING/STRENGTH OF THIS WAVE. WILL LEAVE REMAINDER OF FCST DRY ATTM. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON mi AREA FORECAST DISCUSSION...CORRECTION NATIONAL WEATHER SERVICE MARQUETTE MI 1105 AM EDT SUN AUG 15 2004 .DISCUSSION... PRIMARY SHORTWAVE TROUGH DROPPING ACROSS CNTRL MANITOBA ATTM WITH ATTENDANT FRONT SLIDING MORE E THAN S INTO S MANITOBA INTO NW ONTARIO. CANADIAN RADAR/SFC OBS POINT TO BAND OF SHRA OUT AHEAD OF FRONT AS FAR E AS PICKLE LAKE ONTARIO. OTHER SHRA ON SW PERIFERY OF SHORTWAVE ARE DROPPING INTO NORTHERN ND. MOST THICKER MID CLOUD OUT AHEAD OF THE SHOWERS AND FRONTAL BOUNDARY ARE PUSHING MORE E THAN S. COMBINATION OF THE THINNING CIRRUS/CIRROSTRATUS AND DEVELOPING CU BASED AROUND 6KFT WILL KEEP SKIES PARTLY SUNNY OVR ALL CWA FOR THIS AFTN. SKIES SHOULD BECOME MOSTLY CLOUDY QUICKLY THIS EVENING OVR FAR WEST. FOR MOST PART SW FLOW WILL KEEP ANY LK BREEZE PINNED TO LK SUPERIOR SHORELINE/NEARSHORE AREAS. COULD SEE A WEAK CONVERGENCE ZONE SET UP OVR FAR NE LUCE COUNTY LATER THIS AFTN AS RUC 10KM OUTPUT SHOWS...BUT DESPITE SB INSTABILITY AOA 500J/KG...THINK THE OVERALL DRY AIRMASS (K-INDEX IN LWR TEENS) AND RISING H7-H5 HEIGHTS WILL PROHIBIT ANY LK BREEZE CONVECTION FM DEVELOPING. PUBLISHED GRIDS ALREADY OUT ALONG WITH A MINOR UPDATE TO TEXT ZFPMQT...MAINLY REMOVING ANY MORNING WORDING. JLA && .PREV DISCUSSION...MANITOBA SHRTWV PROGGED TO DIG SE INTO MN BY 12Z MON. LATEST MODELS KEEP ENTIRE CWA DRY TNGT...NOT UNRSNBL CONSIDERING DRY ANTECEDENT AIRMASS/LATE ARRIVAL OF ANY SGNFT H85 THETA-E ADVCTN EVEN OVER THE W AND TRACK OF BEST DPVA/DEEP LYR H85-3 QVECTOR CNVGC/H4-2 DVGC TO THE SW OF FA. BUT INCRSG MID/HI CLD AND SHARPER PRES GRADIENT/SW FLOW WL RESTRICT THE DIURNAL TEMP DECREASE DESPITE LINGERING DRY AIR IN THE LLVLS...ESPECIALLY ACRS THE W WHERE CLDS/ SW FLOW INCRS EARLIER. PREFER THE MORE CONSISTENT GFS/CNDN FOR MON FCST AS THESE MODELS SHOW A FARTHER S TRACK OF THE INCOMING SHRTWV/ASSOCIATED DPVA THAN THE ETA...WHICH MOVES SHRTWV MORE DUE E THAN THE OTHER RUNS...WITH MORE IMPRESSIVE DYNAMICS OVER THE FA/CATEGORICAL OR HI LIKELY ETA MOS POPS. THINK THIS TREND FOR SHARPER DPVA/H85-3 QVECTOR CNVGC/H85 THETA-E ADVCTN NOT IN LINE WITH THE HI AMPLITUDE PATTERN IN PLACE... WHICH WOULD TEND TO FAVOR THE FARTHER S SOLN AND LOWER QPF GENERATED BY THE GFS/CNDN. SO WL CONTINUE GOING 30-40 POPS...WITH HIER VALUES FOR THE WI BORDER ZNS. SINCE GFS FCST LINX WELL ABV ZERO ALL DAY AND GFS MOS TSRA CHCS ARE MINUSCULE...HAVE REMOVED MENTION OF TSRA WITH EXPECTATION FOR LTL INSOLATION AND THAT BEST DYNAMICS/MID LVL COOLING/LLVL MOISTENING/LARGE SCALE DESTABILIZATION WL PASS TO THE S. GFS MOS TMAX LOOK RSNBL WITH CONSIDERABLE CLD COVER. THIS MODEL SHOWS SHRTWV TRACKING TO FAR SW LWR MI BY 12Z MON...WITH AXIS OF HIER MSTR DRIFTING ACRS FA. HAVE OPTED TO RETAIN LO CHC POPS MON NGT UNTIL PASSAGE OF H7 TROF AXIS AS DEPICTED BY GFS. LINGERING SHRA SHOULD END TUE MRNG/EARLY AFTN OVER THE CNTRL/ERN ZNS FOLLOWING PASSAGE OF H7 TROF AXIS AND ARRIVAL OF DNVA/DEEP LYR QVECTOR DVGC/ SUBSIDENCE. ALTHOUGH BOTH ETA/GFS TEND TO PERSIST NR SFC MSTR...MID LVL DRYING RATHER PRONOUNCED WITH KINX FALLING INTO THE LO 20S...AND FCST SDNGS SHOW UNIMPRESSIVE H85-5 LAPSE RATES (BARELY MOIST ADIABATIC). CONSIDERING LACK OF LARGER SCALE BNDRY...HAVE OPTED TO KEEP TUE DRY ONCE MRNG SHRA END EVEN THOUGH GFS GENERATES SOME LGT QPF AND ETA FCST SDNGS SHOW CAPE REACHING 500 J/KG IN THE AFTN. GFS/ETA FCST H85 TEMPS ARND 12C BY 00Z SUPPORT TMAX WELL INTO THE 70S AWAY FM THE COOLING INFLUENCE OF THE LKS. ETA/GFS/UKMET HINT AT ANOTHER QUICK MOVING SHRTWV IN WNW FLOW AND ASSOCIATED WAD WL IMPACT THE UPR GRT LKS LATE TUE NGT...SO HAVE INTRODUCED CHC POPS OVER THE NW ZNS OVRNGT WHERE GFS GENERATES SOME LGT QPF AND SHOWS SSI FALLING BLO 0 WITH H85-5 LAPSE RATES APRCHG 6.5C/KM. THEN INTRODUCED CHC SHRA/TSRA ON WED AFTN AS GFS/CNDN/ETA/ UKMET HAVE TRENDED TOWARD A FASTER COLD FROPA BY WED EVNG. LOWERED FCST TMAX ON WED/TMIN ON THU AND MADE QUICK CHANGES TO SKY/PCPN FCST TO ACCOUNT FOR THIS TREND TO MAINTAIN CONTINUITY WITH SURROUNDING OFFICES. KC && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1040 AM EDT SUN AUG 15 2004 .UPDATE... 1028 SURFACE HIGH IN PLACE ACROSS THE CENTER OF THE STATE...YET ALOFT IS A DIFFERENT STORY WITH UPPER LOW AND DEFORMATION AXIS SEEN ON THE H2O VAPOR LOOP THIS MORNING. AFTER A CHILL START WITH A NEW RECORD LOW FOR MBS AT 43F (46F SET IN 1962)...WE ARE SEEING PLENTY OF SUNSHINE. 12Z SOUNDING REVEALS A COUPLE OF THINGS...MIXING WOULD RESULT IN TEMPS INTO THE LOWER HALF OF THE 70S (GRIDS LOOK GREAT). WITH LIGHT GRADIENT FLOW WE WILL SEE LAKE BREEZE DEVELOPMENT OFF OF LAKE HURON BUT WE WILL KEEP THE CURRENT FORECAST OF DRY GOING AT THIS TIME WITH NOT MUCH INSTABILITY SEEN IN LATEST RUC AND MSAS). FURTHER SOUTH, WHILE LAKE BREEZE DEVELOPMENT WILL LIKELY NOT BE A ISSUE (LAKE/LAND DELTA T NOT ALL THAT IMPRESSIVE), DIFFERENTIAL HEATING BOUNDARIES FROM SHOWERS/THUNDERSTORMS ACROSS LAKE ERIE AND NORTHWEST OHIO MAY BE AN ISSUE. REFERRING BACK TO OUR 12Z SOUNDING, WHEN MODIFIED WITH SURFACE PARCELS OF 73/54 WE HAVE CAPES IN EXCESS OF 1000 J/KG WITH SB LI/S AROUND -3C. 12Z RUC DOES SHOW THE SOUTHERN COUNTIES WITH CAPES CLOSE TO 1000 J/KG WITH LI/S NEAR -4C AND BRN VALUES HIGH AND RESPECTABLE (WEAK SHEAR AND HIGHER CAPE). FOR THESE REASONS WE WILL ADD IN AN ISOLATED SHOWER/THUNDERSTORM FOR THE SOUTH 4 COUNTIES. BGM && .PREV DISCUSSION... ISSUED AT 150 AM EDT LARGE AREA OF HIGH PRESSURE OVER THE GREAT LAKES REGION THIS MORNING. NORMALLY...THAT WOULD SPELL CLEAR SKIES AND NO PRECIPITATION. HOWEVER...LINGERING 500 MB TROUGH AND DEFORMATION ZONE CONTINUES TO CAUSE CLOUDS ACROSS NORTHERN INDIANA/NORTHWEST OHIO/EXTREME SOUTHERN LOWER MICHIGAN. THIS UPPER LEVEL TROUGH WILL ALSO CAUSE MORE CU DEVELOPMENT DURING THE DAY AS WELL. A LITTLE CONCERNED GOING WITH A DRY FORECAST TODAY AFTER SEEING SHOWERS DEVELOP OVER NORTHERN LOWER MICHIGAN LATE YESTERDAY AFTERNOON...RIGHT IN THE CENTER OF THE SURFACE HIGH. 00Z MESOETA FORECASTED SOUNDINGS FOR TODAY DO INDICATE EQUILIBRIUM LEVELS WELL ABOVE -20 C TODAY. LI'S GO SLIGHTLY NEGATIVE...AS 500 MB TEMPS REMAIN COLD...-17 C. NONE-THE-LESS...WILL PROBABLY STICK WITH THE DRY FORECAST TODAY...AS THE TROUGH AXIS SLOWLY SHIFTS TO THE EAST AND WE GET INTO NVA LATER THIS AFTERNOON. LATEST DAY 1 OUT OF SPC INDICATING NO THUNDERSTORMS OVER SOUTHEAST MICHIGAN. MAXES YESTERDAY ENDED UP BEING PREDOMINATELY IN THE LOWER 70S. SHOULD BE ABLE TO ADD A FEW DEGREES TODAY...AS THE AIRMASS CONTINUES TO SLOWLY MODIFY. RIDGING AT ALL LEVELS TO MOVE INTO THE LOWER MICHIGAN TONIGHT...ALLOWING FOR A GOOD RADIATING NIGHT...AS SKIES GO MOSTLY CLEAR/CLEAR. GFS MOS GUIDANCE LOOKS REASONABLE...AND WILL TWEAK DOWN TEMPS IN THE GRIDS. COULD EVEN SEE IT A LITTLE BIT COLDER. WHERE SKIES ARE CLEAR THIS MORNING...TEMPS HAVE FALLEN INTO THE 40S (BAX/MBS). IN FACT...MBS HAS A SHOT AT TYING OR BREAKING THEIR RECORD LOW THIS MORNING (AUGUST 15TH) WHICH IS 46 DEGREES SET IN 1962. FEW IF ANY CHANGES NEED TO BE MADE FOR MONDAY AND TUESDAY. MONDAY MAY BE THE BEST DAY OF THE UPCOMING WEEK...AS THE RIDGE HOLDS...ALLOWING FOR LOTS OF SUNSHINE...AND MAXES CLIMBING TOWARD 80 DEGREES. SHORTWAVE EVIDENT ON THE WATER VAPOR IMAGERY OVER CENTRAL SASKATCHEWAN...STILL ON TRACK TO MOVE THROUGH SOUTHERN LOWER MICHIGAN TUESDAY MORNING...WEAKENING IN THE PROCESS. CHANCE POPS STILL LOOK FINE...WITH A CONTINUED MENTION OF THUNDERSTORMS AS WELL...AS LI'S ARE NEGATIVE. THE FLOW BECOMES ZONAL BY MID-WEEK...MAKING FOR A DIFFICULT FORECAST TIMING SHORTWAVES EJECTING FOR THE NORTHERN PLAINS ON WEDNESDAY...AS THE POLAR VORTEX OVER NORTH CENTRAL CANADA DIVES SOUTH. 00Z GFS AND CANADIAN MODELS INDICATING COLD FRONT TO SWING THROUGH THURSDAY MORNING...WHICH IS IN GOOD AGREEMENT WITH THE CURRENT ZONES...AND WILL THUS MAKE NO CHANGES. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && SF $$ EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 1025 AM CDT SUN AUG 15 2004 .UPDATE...HAVE ISSUED A QUICK UPDATE TO THE FORECAST TO REMOVE PRECIPITATION. HAVE ALSO LOWERED THE CLOUD COVER TO INTRODUCE SUNNY TO MOSTLY SUNNY WORDING. UPDATE TO THE HAZARDOUS WEATHER OUTLOOK HAS ALSO BEEN ISSUED. && .DISCUSSION...PREVIOUS DISCUSSION HANDLES THE CURRENT SITUATION WELL. THE SHORTWAVE AND ASSOCIATED JET STREAK HAVE EXITED OUR FORECAST AREA. THE SHOWERS STILL LINGER ACROSS SOUTHEAST NEBRASKA. SKIES HAVE CLEARED OVER THE REGION AND EXPECT TO SEE TEMPERATURES RISE QUICKLY INTO THE 80S. CURRENTLY RUNNING 5 TO 10 DEGREES WARMER THAN THE SAME TIME YESTERDAY! OTHER CHALLENGE FOR THE NEAR TERM FORECAST IS THE FRONTAL BOUNDARY TONIGHT. TIMING IS PROBLEMATIC AND ABUNDANT MOISTURE SOURCE HAS BEEN CUT OFF. STILL FEEL THAT THERE WILL BE SHRA / TSRA...CHALLENGE WILL BE EXTENT AND DURATION. WITH THE AVAILABLE MODEL DATA...FEEL THAT THE ETA TIMING OF THE FRONTAL PASSAGE IS REASONABLE...HOWEVER THE LACK OF PRECIP IN THE MODEL IS SUSPECT. CURRENTLY THINKING THAT THE POP FIELD WILL BE RIGHT ALONG AND DIRECTLY BEHIND THE FRONT. && .PREV DISCUSSION...ANOTHER ROUND OF MORNING SHOWERS HAS SET UP...THIS TIME IN THE EASTERN CWFA. WILL CONTINUE WITH SMALL COVERAGE OF THIS LIGHT PRECIPITATION THIS MORNING...PER LATEST ETA AND RUC. SHOWERS WILL DIMINISH AROUND MIDDAY...WITH CLOUDS BREAKING UP THEREAFTER. BREEZY CONDITIONS LIKELY THIS AFTERNOON...AND AT LEAST A SMALL WARMUP IS IN STORE FOR THE CWFA. EXPECT THE EVENING TO BE GENERALLY QUIET BUT BREEZY. ANY CHANCE FOR SHOWERS AND THUNDERSTORMS LOOKS LATE TONIGHT IN THE NORTHERN 1/2 TO 2/3RDS OF THE CWFA AS CONVECTION TO THE NORTHWEST MAY WORK INTO THE CWFA. HOWEVER...THIS LOOKS A LITTLE LESS LIKELY GIVEN APPROACHING FRONT APPEARS TO BE SLOWING DOWN...ARE AT LEAST DEPICTED TO. MODELS ARE MUCH SLOWER WITH FRONTAL BOUNDARY NOW. THE ACTUAL FRONT DOESN'T EVEN WORK INTO THE SOUTHERN CWFA UNTIL MONDAY AFTERNOON. PSEUDO-FRONT MAY BE INITIAL AHEAD OF THE MAIN FRONT IF CONVECTION CAN REV-UP TONIGHT INTO CENTRAL NEBRASKA. ANYWAY...MODERATE INSTABILITY BEGINS TO FORM ALONG THE FRONT. ONE OF THE WARMER DAYS IN AWHILE IS EXPECTED MONDAY. CONVERGENCE NEAR THE BOUNDARY MAY SPARK AN ISOLATED TO SCATTERED THUNDERSTORM LATE IN THE AFTERNOON OR EVENING...MAINLY SOUTHERN 2/3RDS OF THE CWFA. NO CHANGES TO SPEAK OF FOR TUESDAY THROUGH SATURDAY. TEMPERATURES TOWARD THE END OF THE WEEK WILL BE TOUCHY WITH ANOTHER ROUND OF COLD AIR SLATED TO HIT THE PLAINS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ LEWIS ne AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ALBANY NY 1035 AM EDT SUN AUG 15 2004 .SHORT TERM (REST OF TODAY)... LATEST VISIBLE SATELLITE PICTURE SHOWS THINNING MID AND HIGH CLOUDS OVER THE SRN ADIRONDACKS AND THE LAKE GEORGE SARATOGA REGION. HAVE ADJUSTED SKY COVER TO PARTLY SUNNY CONDITIONS FROM NORTH TO SOUTH ACROSS THE FCST AREA THROUGH THE AFTERNOON. CLOUDS WILL LINGER THE LONGEST OVER THE MID HUDSON VALLEY...SRN BERKSHIRES AND LITCHFIELD HILLS WHERE A QUARTER TO THREE QUARTERS (LITCHFIELD COUNTY)OF AN INCH OF RAIN FELL FROM THE REMNANTS OF CHARLEY. REMNANTS OF CHARLEY CONTINUE TO RAPIDLY MOVE NORTHEAST THROUGH ERN NEW ENGLAND. LATEST 40 KM RUC AND 12Z MESOETA SHOWS A SHORT WAVE ASSOCIATED WITH 500 HPA TROUGH OVER ERN GREAT LAKES/OH VALLEY MOVING ACROSS WRN NY/ERN GREAT LAKES THIS PM. ALSO MID-LEVEL COLD POOL APPROACHING WRN NY...SO LEFT A LOW CHANCE/SLIGHT CHANCE OF INSTABILITY SHOWERS IN NORTH AND WEST OF KALY THIS AFTERNOON. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 510 AM EDT SUN AUG 15 2004 SYNOPSIS... THE TROPICAL WEATHER SYSTEM WILL MOVE OUT TO SEA OFF CAPE COD THIS MORNING. A RATHER MUGGY AIR MASS WILL REMAIN OVER EASTERN NEW YORK AND WESTERN NEW ENGLAND TODAY. A SHORT WAVE UPPER LEVEL TROUGH IN THE MIDWEST WILL MOVE TOWARD THE NORTHEAST TODAY. IT WILL GENERATE A WEAK WAVE WHICH WILL MOVE NORTHEAST FROM THE MID ATLANTIC REGION. THE SHORT WAVE TROUGH WILL MOVE ACROSS THE NORTHEAST BY MONDAY NIGHT BRINGING DRIER AIR TO THE REGION. A CYCLONE IN CANADA WILL BRING A COOL FRONT TO THE NORTHEAST ON THURSDAY. SOME WARM AIR ADVECTION IN ADVANCE OF THIS...MAY BE ASSOCIATED WITH SCATTERED SHOWERS ON WEDNESDAY. SHORT TERM (TODAY THROUGH MONDAY NIGHT)... THE QUICKER MOVEMENT OF THE AVIATION MODEL HAS WORKED OUT BETTER THAN THE SLOWER ETA OR CANADIAN REGIONAL FORECASTS FOR THE TROPICAL SYSTEM. THE ASSOCIATED RAIN WAS FURTHER SOUTH AND EAST THAN INDICATED BY FORECASTS 24 HOURS AGO. THE RAIN WAS MOVING QUICKLY EAST ACROSS NEW ENGLAND TOWARD DAYBREAK. THE FORECAST SOUNDINGS FROM THE MESOETA MODEL AND THE AVIATION MODEL INDICATED SOME INSTABILITY TODAY...AND IT IS POSSIBLE THAT SOME LIGHT SHOWERS MAY POP UP THIS AFTERNOON...ESPECIALLY NORTH OF THE CAPITAL DISTRICT. THE SHORT WAVE APPROACHING FROM THE MIDWEST IS FORECAST TO GENERATE SOME PRECIPITATION ACROSS THE COUNTY WARNING AREA TONIGHT AND MONDAY. THE EXCEPTION IS THE FORECAST FROM THE CANADIAN GLOBAL MODEL WHICH KEEPS THE MOISTURE TO THE EAST OF THE REGION. WE MENTIONED THE CHANCE OF SHOWERS FOR TONIGHT AND MONDAY...WITH THE BEST CHANCE IN SOUTHEASTERN NEW YORK. AS ANY SYSTEM THAT FORMS MOVES EAST MONDAY...DRIER AIR WILL TAKE HOLD BY MONDAY EVENING. THE MAXIMUM AND MINIMUM TEMPERATURES FORECAST THROUGH MONDAY NIGHT WERE FAIRLY CLOSE TO THE LATEST GUIDANCE AND WERE NOT CHANGED MUCH. THE BIGGEST DIFFERENCES IN TEMPERATURE GUIDANCE WERE FOR MONDAY...WHERE LOWER VALUES WERE SUGGESTED. WE BACKED OFF A BIT FROM THE PREVIOUS FORECAST FOR MONDAY. LONG TERM (TUESDAY THROUGH SATURDAY)... A STRETCH OF DRY WEATHER IS INDICATED BY ALL MODELS THROUGH TUESDAY. THERE IS SOME QUESTION AS TO WHETHER SHOWERS WILL BREAK OUT OR NOT TUESDAY NIGHT. THE ETA AND AVIATION BOTH WEAKLY SUGGEST THAT THIS COULD OCCUR...WHILE THE CANADIAN GLOBAL FORECASTS DRY WEATHER. WE BOOSTED THE PROBABILITY OF RAINFALL TO 20 PERCENT FOR TUESDAY NIGHT AND MAINTAINED IT AT 30 PERCENT FOR WEDNESDAY. WE KEPT A SMALL CHANCE OF SHOWERS IN THE FORECAST THROUGH FRIDAY NIGHT. THE SURFACE FRONT STALLS OVER THE REGION ON THE WEEKEND AND THE AVIATION MODEL GENERATES WAVES WHICH RESULT IN RAINFALL. THE CANADIAN ENSEMBLE FORECAST ON THE OTHER HAND...MAINTAINS ONLY ABOUT A 20 PERCENT CHANCE OF RAIN ON THE WEEKEND...WITH SEVERAL MEMBERS HAVING DRY FORECASTS WITH AN ANTICYCLONE IN THE VICINITY. WE OPTED TO MAINTAIN THE DRY WEATHER FROM THE PREVIOUS ZONES AND GRIDS FOR SATURDAY. WE ARE EXPECTING TO GO FOR ABOUT A 20 PERCENT CHANCE OF PRECIPITATION ON THE SUNDAY FORECAST. AVIATION...REMNANTS OF CHARLIE WL ONLY IMPACT AREA THRU ERLY MRNG HRS. WL LEAVE KGFL DRY AND ONLY PUT RAIN IN AT KALB FOR 3 HOURS 09Z-12Z AND KPOU THRU 12Z. LOWEST CIGS AND VSBYS WL BE AT KPOU WITH MVFR/IFR CNDTNS TIL 12Z. AFT 12Z VFR CNDTNS XCPT POTENTIAL FOR SCT SHRA LATE AFT INTO THIS EVNG AT KGFL/KALB AHD OF UPPER TROF AND VORT AXIS MOVG INTO ERN GRTLKS WHICH LOOKS TO RESULT IN SOM MVFR CNDTNS AFT 22Z. HYDROLOGY...THERE WAS NO MORE THAN ABOUT HALF AN INCH OF RAINFALL...AND THE RIVERS AND STREAMS ARE WELL WITHIN THEIR BANKS ACROSS THE REGION. RAINFALL FOR LATE TONIGHT AND MONDAY IS LOW CONFIDENCE AS THE MODELS VARY SO MUCH. HOWEVER...ANY RAIN THAT OCCURS IS NOT EXPECTED TO BE ENOUGH TO CAUSE FLOODING. AFTER A DRY DAY TUESDAY...THERE IS A CHANCE OF SCATTERED SHOWERS FOR MUCH OF THE BALANCE OF THE WEEK. BUT RAINFALL IS NOT LIKELY TO BE WIDESPREAD...AND SHOULD HAVE LITTLE IMPACT UPON THE RIVERS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NY...NONE. VT...NONE. && $$ SHORT TERM (UPDATE)...WASULA ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 925 PM EDT SUN AUG 15 2004 TALE OF TWO HALVES...WITH WESTERN NC MUCH DRIER...WHILE EASTERN HALF CONTINUES TO BE UNDER TROPICAL PLUME. AREA OF RAIN OVER THE PIEDMONT REFUSES TO GO WAY. REFLECTIVITY AND SRM PATTERN SHOWS A BAROCLINIC LEAF LIKE STRUCTURE TO THE RAIN INDICATING S/W ALOFT. KRAX AND SURROUNDING NWS RADAR VWP PLOTS ALSO SHOW SW FLOW ALOFT...INDICATING THAT THE 700 TROUGH REMAINS WEST OF AREA. TROPICAL PLUME SLOWLY BEING SQUEEZED OVER COASTAL CAROLINA AS MID/UPPER TROUGH SLOWLY BUILDS EAST. WILL CONTINUE TO SEE RAIN/DRIZZLE OVER EASTERN HALF OF CWA UNTIL WESTERLY 700H FLOW MOVES IN. BOTH THE RUC/ETA12 SEEM TO HAVE GOOD HANDLE ON CURRENT CONDITIONS AND BRING WESTERLY FLOW INTO THE EAST BY 9Z. WILL UPDATE FORECAST TO REFLECT AN EXTENSION OF POPS OVER THE EAST THROUGH THE OVERNIGHT HOURS. WITH RAIN CONTINUING OVERNIGHT WILL RAISE OVERNIGHT TEMPERATURES ONE CATEGORY ALL ZONES. .PREV DISCUSSION (TONIGHT THROUGH WEDNESDAY NIGHT)... THIS EVENING...LIFT AND SATURATION IN THE EASTERN HALF OF THE CWA AT 21Z AS DEPICTED BY THE RUC CLEARS OUT OF THE CWA TO THE NORTHEAST BY 03Z. HIGH POPS WILL BE CONTINUED IN THE EAST INTO THIS EVENING WITH ONLY A SLIGHT CHANCE OF RAIN OR JUST CHANCE OF DRIZZLE IN THE WEST EARLY. POPS WILL DIMINISH BELOW THRESHOLDS AROUND MIDNIGHT. WEAK SURFACE FLOW INLAND BEHIND A WEAK COASTAL LOW SHOULD PROMPT LOW STRATUS AND FOG. MODELS DEPICT SATURATED LOWEST LAYERS THROUGH DAYBREAK. CONSENSUS MIN TEMP GUIDANCE SUGGESTS 62-66 ACROSS THE CWA. MONDAY...HIGH PRESSURE OVER THE UPPER OHIO EXTENDS WEAKLY INTO CENTRAL NC AS WEAK RIDGING TAKES PLACE ALOFT. DRYNESS ALOFT SHOULD ALLOW SUN TO MIX OUT ANY RESIDUAL LOWER CLOUDS...BUT SHALLOW SATURATION ATOP THE MIXED LAYER SHOULD RESULT IN SOME CU/STRATO CU IN THE AFTERNOON. GIVEN NEAR SATURATED SOILS IN MANY SECTIONS... MAX TEMPERATURES WILL BE PLAYED TO THE LOW SIDE OF GUIDANCE... MAINLY 80-85. TUE-WED...A BROAD TROUGH ALOFT LINGERS IN THE MIDWEST WITH A SOMEWHAT STAGNANT FLAT PRESSURE PATTERN AT THE SURFACE. WEAK LOW PRESSURE IN THE UPPER TENNESSEE VALLEY TO SOUTHERN APPALACHIANS GIVES WAY TO EXPANDING HIGH PRESSURE OVER THE GULF STREAM ATLANTIC. LOW LEVEL FLOW EVOLVES TO BECOME INCREASINGLY SW. MOIST LAYERS REMAIN IN THE LOWER TO MID LEVELS AND WITH MID LEVEL LAPSE RATES IN THE 5.5-6.0 C/KM RANGE...DIURNAL HEATING MAY POP A SHOWER OR ISOLATED THUNDERSTORM EACH LATE AFTERNOON. LACK OF ANY AIRMASS BOUNDARIES OR CONVERGENCE MECHANISMS SHOULD KEEP POPS IN THE SLIGHT CHANCE CATEGORY. NO SIGNIFICANT DEVIATIONS FROM GUIDANCE MAX/MINS. && .LONG TERM (THURSDAY THROUGH SUNDAY)... MAINLY DIURNAL CONVECTION AND SLIGHTLY ABOVE NORMAL TEMPS THURSDAY AND FRIDAY WITH A SOUTHWEST SURFACE FLOW AND A NEARLY ZONAL FLOW ALOFT. A CLOSED LOW OVER THE HUDSON BAY SWINGS A TROUGH AXIS ACROSS THE CENTRAL CONUS ON SATURDAY...LOWERING HEIGHTS IN THE EAST AND INCREASING MOISTURE FLOW FROM THE GULF. GFS INDICATES A FROPA LATE SATURDAY/EARLY SUNDAY. WILL INCREASE CLOUDS AND POPS A BIT BOTH DAYS. THE REMNANTS OF EARL COULD ALSO BECOME A PLAYER IN NEXT WEEKEND'S WEATHER IF IT GETS PICKED UP BY THE TROUGH. && .AVIATION... THROUGH THE AFTERNOON AND EVENING...IFR VIS AND CIGS IN ALL LOCATIONS AND TEMPO LIFR EAST WITH CURRENT RAINFALL. RUC SHOWS THE AREA OF LIFT WITH THIS PRECIP CLEARING THE AREA BETWEEN 21Z AND 00Z. DO NOT EXPECT CEILINGS TO GET ANY HIGHER THAN MVFR IN ANY LOCATION WITH THE CURRENT WEAK WEDGE PATTERN CHANGING LITTLE. PLENTY OF LOW LEVEL MOISTURE SHOULD AGAIN BRING LOW STRATUS TO THE ENTIRE AREA OVERNIGHT...BELOW 500 FT. CEILINGS SHOULD LIFT QUICKLY AFTER 12Z TOMORROW AS WINDS TURN MORE WESTERLY BEHIND THE 700 MB TROUGH PASSAGE. && .RAH WATCHES/WARNINGS/ADVISORIES... NC...NONE. && $$ UPDATED BY: nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 200 PM EDT SUN AUG 15 2004 .SHORT TERM (TONIGHT THROUGH WEDNESDAY NIGHT)... THIS EVENING...LIFT AND SATURATION IN THE EASTERN HALF OF THE CWA AT 21Z AS DEPICTED BY THE RUC CLEARS OUT OF THE CWA TO THE NORTHEAST BY 03Z. HIGH POPS WILL BE CONTINUED IN THE EAST INTO THIS EVENING WITH ONLY A SLIGHT CHANCE OF RAIN OR JUST CHANCE OF DRIZZLE IN THE WEST EARLY. POPS WILL DIMINISH BELOW THRESHOLDS AROUND MIDNIGHT. WEAK SURFACE FLOW INLAND BEHIND A WEAK COASTAL LOW SHOULD PROMPT LOW STRATUS AND FOG. MODELS DEPICT SATURATED LOWEST LAYERS THROUGH DAYBREAK. CONSENSUS MIN TEMP GUIDANCE SUGGESTS 62-66 ACROSS THE CWA. MONDAY...HIGH PRESSURE OVER THE UPPER OHIO EXTENDS WEAKLY INTO CENTRAL NC AS WEAK RIDGING TAKES PLACE ALOFT. DRYNESS ALOFT SHOULD ALLOW SUN TO MIX OUT ANY RESIDUAL LOWER CLOUDS...BUT SHALLOW SATURATION ATOP THE MIXED LAYER SHOULD RESULT IN SOME CU/STRATO CU IN THE AFTERNOON. GIVEN NEAR SATURATED SOILS IN MANY SECTIONS... MAX TEMPERATURES WILL BE PLAYED TO THE LOW SIDE OF GUIDANCE... MAINLY 80-85. TUE-WED...A BROAD TROUGH ALOFT LINGERS IN THE MIDWEST WITH A SOMEWHAT STAGNANT FLAT PRESSURE PATTERN AT THE SURFACE. WEAK LOW PRESSURE IN THE UPPER TENNESSEE VALLEY TO SOUTHERN APPALACHIANS GIVES WAY TO EXPANDING HIGH PRESSURE OVER THE GULF STREAM ATLANTIC. LOW LEVEL FLOW EVOLVES TO BECOME INCREASINGLY SW. MOIST LAYERS REMAIN IN THE LOWER TO MID LEVELS AND WITH MID LEVEL LAPSE RATES IN THE 5.5-6.0 C/KM RANGE...DIURNAL HEATING MAY POP A SHOWER OR ISOLATED THUNDERSTORM EACH LATE AFTERNOON. LACK OF ANY AIRMASS BOUNDARIES OR CONVERGENCE MECHANISMS SHOULD KEEP POPS IN THE SLIGHT CHANCE CATEGORY. NO SIGNIFICANT DEVIATIONS FROM GUIDANCE MAX/MINS. && .LONG TERM (THURSDAY THROUGH SUNDAY)... MAINLY DIURNAL CONVECTION AND SLIGHTLY ABOVE NORMAL TEMPS THURSDAY AND FRIDAY WITH A SOUTHWEST SURFACE FLOW AND A NEARLY ZONAL FLOW ALOFT. A CLOSED LOW OVER THE HUDSON BAY SWINGS A TROUGH AXIS ACROSS THE CENTRAL CONUS ON SATURDAY...LOWERING HEIGHTS IN THE EAST AND INCREASING MOISTURE FLOW FROM THE GULF. GFS INDICATES A FROPA LATE SATURDAY/EARLY SUNDAY. WILL INCREASE CLOUDS AND POPS A BIT BOTH DAYS. THE REMNANTS OF EARL COULD ALSO BECOME A PLAYER IN NEXT WEEKEND'S WEATHER IF IT GETS PICKED UP BY THE TROUGH. && .AVIATION... THROUGH THE AFTERNOON AND EVENING...IFR VIS AND CIGS IN ALL LOCATIONS AND TEMPO LIFR EAST WITH CURRENT RAINFALL. RUC SHOWS THE AREA OF LIFT WITH THIS PRECIP CLEARING THE AREA BETWEEN 21Z AND 00Z. DO NOT EXPECT CEILINGS TO GET ANY HIGHER THAN MVFR IN ANY LOCATION WITH THE CURRENT WEAK WEDGE PATTERN CHANGING LITTLE. PLENTY OF LOW LEVEL MOISTURE SHOULD AGAIN BRING LOW STRATUS TO THE ENTIRE AREA OVERNIGHT...BELOW 500 FT. CEILINGS SHOULD LIFT QUICKLY AFTER 12Z TOMORROW AS WINDS TURN MORE WESTERLY BEHIND THE 700 MB TROUGH PASSAGE. && .RAH WATCHES/WARNINGS/ADVISORIES... NC...NONE. && $$ SHORT TERM...RFG LONG TERM/AVIATION...DGS nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 945 AM EDT SUN AUG 15 2004 .SHORT TERM (REST OF TODAY THROUGH TONIGHT)... FORECASTS HAVE BEEN UPDATED TO REFLECT MORE WIDESPREAD RAIN AND CLOUDINESS OVER THE AREA THIS MORNING. MIDLEVEL SHORT WAVE DYNAMICS ARE STRONGER THAN PREVIOUS MODEL INDICATIONS RIDING UP THROUGH CENTRAL NC TODAY. RUC DEPICTS STRONG MIDLEVEL LIFT TOPPING OUT OVER THE AREA AROUND 17Z FOLLOWED BY SUBSIDENCE FROM THE SW LATER THIS AFTERNOON AND EVENING. THE ADDITIONAL CLOUDS AND RAIN AND NORTHERLY SURFACE FLOW SHOULD KEEP TEMPERATURES DOWN IN THE 60S THIS MORNING SLOWLY RISING INTO THE LOWER TO MID 70S LATE IN THE DAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NC...NONE. && $$ SHORT TERM (UPDATE)...RFG nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1028 PM EDT SUN AUG 15 2004 .SHORT TERM (REST OF TONIGHT THROUGH MONDAY)... UPPER AIR ANALYSIS THIS EVENING...DESPITE A GAPING HOLE OF MISSING DATA FROM THE OHIO VALLEY...SUGGESTS A SHORTWAVE IS WORKING TOWARD THE CWFA THIS EVENING THIS FEATURE IS NOTICEABLE ON THE WATER VAPOR IMAGERY. AHEAD OF THIS FEATURE...WE HAVE SEEN ANTICIPATED DEVELOPMENT OF UPSLOPE SHOWERS ACROSS THE NORTH CAROLINA MOUNTAINS. OBSERVED SOUNDINGS SHOW SOME UPGLIDE CONTINUING INTO THE NORTH CAROLINA PIEDMONT AND FOOTHILLS...OVER A MOISTURE BOUNDARY LOCATED ALONG THE COASTAL PLAIN. SATELLITE IMAGERY HAS SHOWN A MARKED INCREASE IN LOW LEVEL CLOUDS IN THE PAST FEW HOURS AHEAD OF THE SHORTWAVE WITH A DECOUPLED ATMOSPHERE. RUC AND 12 KM ETA CONTINUE PUSHING THE SHORTWAVE ACROSS THE CWFA THROUGH THE OVERNIGHT. WE SHOULD SEE AN EROSION OF THE LOW CLOUDS LATE FRM THE SOUTH AND WEST...ALTHOUGH WE DID PAINT MOSTLY CLOUDY FOR THE REMAINDER OF THE OVERNIGHT ACROSS THE HIGHER TERRAIN. EASTERN ZONES...DESPITE SHALLOW NATURE OF THE MOISTURE...MAY REMAIN NEARLY OVERCAST UNTIL VERY LATE TONIGHT UNTIL THE SHORTWAVE AXIS HAS SHIFTED SUFFICIENTLY EAST FOR EROSION TO BEGIN THERE. SATELLITE IMAGERY HAS SHOWN A NARROW CLOUD MINIMA BAND JUST DOWNSTREAM OF THE EASTERN EXTENT OF THE BLUE RIDGE...BUT THIS HAS BEEN SHRIVELING WITH TIME. FOR THE FEW MINUTES THAT SKIES WERE ACTUALLY MOSTLY CLEAR HERE AT OUR AIRPORT LOCATION...GROUND FOG DEVELOPED RAPIDLY. WE SUSPECT THAT IF ANY LOCATIONS BREAK OUT FOR LONG IN THE PREDAWN HOURS IN THE EXISTANT AIR MASS...ANY FOG THAT DEVELOPS MAY BE A BIT ON THE DENSE SIDE BUT FOR NOW WILL LEAVE THE PATCHY FOG WORDING AS PREVIOUSLY ADVERTISED. TEMPEARTURES SEEM ON TRACK MOST LOCATIONS...BUT WE DID BUMP UP MINS A DEGREE OR TWO ALONG AND EAST OF INTERSTATE 77...WHERE A MOSTLY CLOUDY OVERNIGHT COULD HOLD TEMPERATURES UP. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 244 PM EDT SUN AUG 15 2004 SHORT TERM (TONIGHT THROUGH WEDNESDAY)... UPPER LEVEL TROUGH REMAIN OVER EASTERN SEABOARD THROUGH WEDNESDAY... WHILE SURFACE RIDGE MOVES FROM CENTER OF NATION TO WESTERN ATLANTIC. AREA REMAINS IN A WEAK E WIND COMPONENT TONIGHT...KEEPING CLOUD COVER UP AND A CHANCE OF SHOWERS EARLY. BY LATE EVENING AN UPPER LEVEL IMPULSE ACCOMPANIED BY THE RIGHT ENTRANCE REGION OF A JET MAX APPROACH MOUNTAINS. WILL SHIFT EMPHASIS OF POPS TO MOUNTAINS AROUND MIDNIGHT. WINDS BACK AGAIN TO LIGHT NE AROUND DAWN MON. WILL CARRY PATCHY FOG AROUND DAWN IN HIGH RH. MODELS VEER FLOW TO UPSLOPE LATE MON AFTERNOON IN RESPONSE TO A SURFACE WAVE THEY DEVELOP. ALTHOUGH UPPER LEVEL FORCING WEAK...AIR MASS BECOMES MORE UNSTABLE...AND WILL CARRY POPS AGAIN FROM LATE AFTERNOON UNTIL LATE EVENING...BEST IN HIGHER TERRAIN. LATE MON NIGHT AND TUE MODELS BACK WINDS TO NE THEN VEER TO UPSLOPE BY AFTERNOON... AGAIN FAVORING THE POPS IN W. LATE TUE NIGHT WIND FINALLY VEERS TO SW. MOISTURE INCREASES FROM W ON WED AS ANOTHER UPPER LEVEL IMPULSE APPROACHES...SUPPORTING CHANCE POPS ACROSS AREA. MAX TEMPERATURES BELOW NORMAL UNDER INFLUENCE OF TROUGH AND CLOUD COVER...WHILE CLOUDS HOLD MIN TEMPERATURES NEAR CLIMATOLOGY. LONG TERM (WEDNESDAY NIGHT THROUGH SUNDAY)... MEAN FLOW SHIFTS TO SOUTHWESTERLY THURSDAY AFTERNOON AHEAD OF DEEPENING TROUGH OVER THE CENTRAL PLAINS. BY THURSDAY MORNING...THIS SHOULD RESULT IN MOISTURE AND CLOUDS INCREASING FROM WEST. STRONG SHORTWAVE PROGGED TO APPROACH THE AREA COINCIDENT WITH A FAIRLY STRONG COLD FRONT SATURDAY. GFS SEEMS TO BE OVERDOING MOISTURE IN THE AREA FRIDAY NIGHT AND SATURDAY MORNING...APPARENTLY ADVECTING MOISTURE OFF TROPICAL SYSTEM EARL WHICH MAY BE IN THE GULF AT THAT TIME. NEVERTHELESS...THERE SHOULD BE A GOOD FLUX OF GULF MOISTURE AHEAD OF THE FRONT BEGINNING FRIDAY AFTERNOON...THUS HAVE CHANCE POPS THROUGH SUNDAY MORNING. HAVE GONE WITH TEMPS NEAR NORMAL THURSDAY AND FRIDAY...THEN A LITTLE BELOW NORMAL THROUGH THE WEEKEND WITH CLOUDS AND PRECIP. AS THE WEEKEND NEARS...FORECAST MAY AGAIN DEPEND HEAVILY ON FUTURE TRACK OF THE TROPICAL SYSTEM. AVIATION... COLD AIR DAMMING WAS STRONGER THAN ORIGINALLY EXPECTED TODAY. MOST TAF SITES ARE STILL CARRYING MVFR CIGS...THOUGH AN AREA OF IFR CIGS AND VSBYS PERSISTS ACROSS THE NC PIEDMONT...INCLUDING KCLT. HAVE GRADUALLY INCREASED CIGS ALL TAF SITES THROUGH THE LATE AFTN AND EARLY EVENING...THOUGH HAVE HELD ON TO IFR CIGS AT CLT UNTIL 02 UTC. IT IS ALWAYS DIFFICULT TO TIME EROSION OF CAD EVENTS...AND IT MAY BE THAT LOWER CIGS AND VSBYS WL NEED TO BE CONTINUED FOR LONGER THAN IS IN THE TAFS AT JUST ABOUT ANY LOCATION. PROVIDED WE DO CLEAR LATER TNGT...FOG WL THEN BECOME A PROBLEM. WITH WET GROUND AND LGT WNDS...HAVE TAKEN ALL SITES DOWN TO MVFR VSBY AFTER MIDNIGHT. HAVE KAND GOING IFR VSBY FOR A FEW HOURS AS WELL. THERE IS CERTAINLY THE POTENTIAL FOR CONSIDERABLY GREATER REDUCTIONS TO VSBY THAN ARE CURRENTLY IN THE TAFS...DEPENDANT UPON CLEARING AND LIGHTNESS OF THE WINDS. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SHORT TERM (UPDATE)...SAB sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 915 PM EDT SUN AUG 15 2004 .SHORT TERM /TONIGHT/...OLD FRONTAL BOUNDARY ACROSS THE AREA IS TAPPING INTO DEEP MOISTURE AND BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA. RUC AND GFS SEEM TO HAVE THE BEST HANDLE OF THE CURRENT SITUATION. BOTH TAKE THE SHORT WAVE CURRENTLY OVER CENTRAL TN EAST OVERNIGHT AND PUSH THE FRONT OFF THE CAROLINA COAST...THROUGH THE COASTAL WATERS INTO EXTREME SOUTHERN GEORGIA BY DAY BREAK. LIKE LAST NIGHT...EXPECT SHOWERS AND THUNDERSTORMS TO CONTINUE ALONG THE BOUNDARY THROUGH THE OVERNIGHT HOURS...SO WILL KEEP IN MENTION OF POPS THROUGH THE NIGHT EXCEPT EXTREME INLAND COUNTIES WHERE PRECIP SHOULD CUT OFF SOON AFTER MIDNIGHT. WILL TWEAK WINDS SLIGHTLY AS WELL AS INCREASE CLOUD COVER TO MOSTLY CLOUDY. && .MARINE...FRONTAL BOUNDARY DRAPED ACROSS LAND AREAS OF THE CWA THIS EVE...EXTENDING SW TO THE NE GULF OF MEX. WEAK LOW PRES ALONG THE FRONT BETWEEN TLH AND PFN THIS EVE TO MOVE NE UP THE FRONT...ALLOWING FOR THE TAIL END OF THE BOUNDARY TO PUSH THRU SC WATERS LATE TONIGHT/EARLY MON. THIS WILL ALLOW FOR WINDS TO SHIFT TO N ON SC WATERS...AND BECOME VRBL ON GA WATERS. SEAS TO REMAIN 3 FT OR LESS WITH LIGHT WIND REGIME AND LITTLE OR NO SWELL ACTION. WILL MAKE THE NECESSARY ADJUSTMENTS FOR THE EVE UPDATE. WILL ALSO RAISE COVERAGE OF CONVECTION ON GA WATERS BASED ON RADAR/SATELLITE FOR EARLY TONIGHT. && .AVIATION...CIGS TO CONTINUE LOWERING OVERNIGHT...AND EXPECTING IFR CONDITIONS OVERNIGHT AND MON MORNING. CAN NOT RULE OUT SOME ISOLATED SHOWER OR TSTM ACTIVITY OVERNIGHT WITH FRONTAL BOUNDARY ACROSS THE AREA...AND AGAIN WITH THE SEA BREEZE MON AFTERNOON...BUT CHANCES NOT HIGH ENOUGH TO INCLUDE IN THE TAF FOR EITHER SITE. LIGHT WINDS THRU THE 24 FCST PERIOD. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ JR/PM sc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE COLUMBIA SC 1232 PM EDT SUN AUG 15 2004 .UPDATE... WEAK SURFACE FRONT IS STALLED OUT TO THE SOUTH OF THE CAE CWA FOR THE TIME BEING. WEAK WEDGE LIKE CONDITIONS ARE PERSISTING OVER THE AREA. RUC MODEL KEEPS WEDGE OVER AREA THIS AFTERNOON WITH NORTHEAST WINDS...POSITIVE LIS AND WEAK OVERRUNNING IN THE LOWER LEVELS. PLAN ON UPDATE TO LOWER HIGH TEMPERATURES AT LEAST TWO CATEGORIES. ALSO WILL TAKE OUT THUNDER NORTH AND CENTRAL PARTS BUT WILL KEEP IN SOUTHERN AREAS. && .PREV DISCUSSION... SATELLITE SHOWS LOTS OF CLOUDS STREAMING N/NE ACROSS THE AREA THIS MORNING. WV LOOP SHOWS MOISTURE ACROSS THE CNTRL/ERN PORTION OF THE STATE. REGIONAL 88D COMPOSITE SHOWS SCATTERED SHRA/EVEN A FEW TSRA ACROSS THE CWA MOVING NWD. BOTH ETA/GFS NOT DIFFERING TOO MUCH ON OVERALL PATTERN ACROSS THE AREA THROUGH THE SHORT TERM PERIOD...BUT DIFFERENCES SHOW UP IN THE DETAILS. GFS A BIT STRONGER WITH MID/UPPER LEVEL TROUGH TO THE WEST OF THE AREA THIS MORNING AND ALSO STRONGER WITH SHORTWAVE RIDING UP THE COAST. ALSO GFS APPEARS TO BE HANDLING THE UPPER LEVEL DIVERGENCE A BIT BETTER...ALONG WITH LOW LEVEL MOISTURE TRANSPORT AND CONVERGENCE ACROSS THE AREA. BOTH ETA/GFS INDICATE THAT WAA... LOW LEVEL MOISTURE CONVERGENCE WILL LIFT NEWD LATER THIS MORNING AND EXPECT PCPN TO SHIFT NE AWAY FROM THE CWA AROUND MIDDAY. WILL UP POPS TO CHANCE ACROSS MOST AREAS THIS MORNING FROM CHANCE W TO LOW LIKELY E. PW VALUES HIGHEST E...CLOSE TO 2.0 INCHES AND EXPECT SOME LOCALLY HEAVY RAIN. AIRMASS FORECASTED TO BECOME MODERALY UNSTABLE THIS AFTERNOON WITH SOME DRIER AIR ALOFT...COULD HAVE SOME ADDITIONAL WIDELY SCT/SCT SHRA/TSRA THIS AFTERNOON/EVENING...BUT LIMITING FACTORS WILL BE HOW LONG CLOUDS LINGER/AMOUNT OF INSOLATION AND IF PCPN THIS MORNING WILL HELP TO STABILIZE AIRMASS. WITH CLOUDS AND PCPN THIS MORNING FINALLY TAPERING OFF AROUND MIDDAY...EXPECT AFTERNOON MAXES TO BE LOWER THAN MOST GUIDANCE NUMBERS BUT HIGHER THAN COOL MAV. MID/UPPER LEVEL TROUGH TO OUR WEST TODAY WILL GRADUALLY PUSH THROUGH THE AREA ON MONDAY...AS FLOW BECOMES MORE WESTERLY. ALTHOUGH MOISTURE A BIT LIMITED ON TUESDAY AND SOME CAPPING INDICATED ON FORECAST SOUNDING...WITH SHORTWAVE APPROACHING DURING THE AFTERNOON ALONG WITH AIRMASS WEAKLY UNSTABLE WILL KEEP SLIGHT CHANCE OF AFTERNOON/EVENING SHRA/TSRA. WITH FLOW WESTERLY... SHORTWAVE SEEMS TO LINGER ACROSS THE AREA ON TUESDAY ALONG WITH WEAKLY/MODERATELY UNSTABLE AIRMASS. WILL CONTINUE WITH A SLIGHT CHANCE...ALTHOUGH SOME WEAK CAPPING MAY SUPPRESS DEVELOPMENT ONCE AGAIN. GUIDANCE AND LOCAL EQUATIONS CLOSE THROUGH THE PERIOD...EXCEPT FOR MUCH COOLER MAV GUIDANCE TODAY. WILL GENERALLY STAY CLOSE TO CONSENSUS VALUES THROUGH THE PERIOD. THROUGH THE REMAINDER OF THE WEEK...GFS SHOWS MID/UPPER LEVEL FLOW REMAINING RATHER WESTERLY ACROSS THE AREA. SHORTWAVE ENERGY MOVES TO OUR N ON WED ACROSS THE OH RIVER VALLEY. CYCLONIC H85 WARM ADVECTION WILL CONTINUE TO SUPPORT SHOWERS THIS MORNING. EXPECT OCCASIONAL MVFR CONDITIONS IN THE SHOWERS. THE ETA AND GFS SHOW THE WARM ADVECTION ENDING BY MIDDAY...BUT WITH HEATING EXPECT SCATTERED THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 07/31 sc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1201 PM EDT SUN AUG 15 2004 .SHORT TERM (REST OF TONIGHT)... UPDATING TO PROLONG WEDGE LIKE CONDITIONS LEE OF MOUNTAINS. WILL MENTION ISOLATED THUNDER AS INSTABILITY MARGINAL. LEFT SKY GRIDS ALONE AS THEY WENT PARTLY CLOUDY LATE. DROPED MAXIMUM TEMPERATURES ANOTHER DEGREE OR TWO. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 859 AM EDT SUN AUG 15 2004 SHORT TERM (REST OF TODAY)... SURFACE FRONT LOCATED OVER SC MIDLANDS THIS MORNING. ISENTROPIC LIFT OVER THIS BOUNDARY PRODUCING CLOUDS AND PRECIP ACROSS MUCH OF LEE THIS MORNING...AND HAVE CONTINUED THIS TREND THROUGH THE MORNING HOURS. INCREASED CLOUD COVER MUCH OF DAY...AND LOWERED TEMPERATURES ABOUT 1 DEGREE...2 IN FAR S. UPDATED WITH RUC WINDS...THOUGH STILL NE. EXPECT AFTERNOON CONVECTION TO BE BEST IN MOUNTAINS WHERE LESS CLOUD COVER EXISTS. INCREASD POPS TO CHANCE E PORTION THIS AFTERNOON TO ACOUNT FOR ACTIVITY CLOSER TO BOUNDARY AND BETTER MOISTURE...AND FOR BETTER MATCH WITH NEIGHBORING OFFICES. THE FOLLOWING WAS ORIGINALLY ISSUED AT 335 AM EDT SUN AUG 15 2004 SHORT TERM (TODAY THROUGH MONDAY NIGHT)... WV IMAGERY INDICATES THAT THE BACK EDGE OF THE DEEP MOISTURE STILL LINGERS OVER THE EXTREME EASTERN PORTION OF THE CWFA. SURFACE BOUNDARY REMAINS STALLED FROM THE MIDLANDS INTO THE NC COASTAL PLAIN. UPGLIDE OVER THIS FEATURE COMBINED WITH WEAK UPSLOPE FLOW AND ABUNDANT LOW LEVEL MOISTURE IS RESULTING IN WIDESPREAD LOW CLOUDS ACROSS THE AREA. IN ADDITION...AN AREA OF SHOWERS THAT DEVELOPED EARLIER IN THE UPGLIDE/DEEP MOISTURE REGIME ACROSS THE MIDLANDS WILL CLIP THE EXTREME SOUTHEAST CORNER OF OUR AREA THIS MORNING. WE'RE EVEN SEEING SOME SHOWERS DEVELOP IN THE DRIER AIR ACROSS THE UPSTATE. WE WILL GO AHEAD AND INCLUDE A CHANCE POP FOR THIS MORNING...ROUGHLY SOUTH OF I-40...AND FROM I-26 EAST TO HANDLE THIS ACTIVITY. THE DEEP MOISTURE WILL FINALLY BE SHUNTED EAST OF THE AREA BY LATE IN THE MORNING...AND UPGLIDE FLOW WILL WEAKEN AS THE BOUNDARY BEGINS TO WASH OUT. HOWEVER...A WEAK UPSLOPE COMPONENT WILL BE MAINTAINED THROUGH MOST OF THE DAY. IN ADDITION...THE AREA WILL REMAIN UNDER THE INFLUENCE OF THE RRQ OF AN UPPER JET STREAK. THEREFORE...A LOW CHANCE POP IS PROBABLY WARRANTED ACROSS THE HIGHER TERRAIN AND NC FOOTHILLS THIS PM. HAVE TAPERED POPS DOWN TO SLIGHT CHANCE ACROSS THE NC MNTNS/FHILLS AFTER EARLY EVENING. HOWEVER...THE UPPER TROUGH WILL MOVE OVER THE AREA TONIGHT...POSSIBLY ALLOWING SOME CONVECTION TO LINGER INTO THE OVERNIGHT HOURS. AS THE TROUGH SWINGS OVER THE AREA TONIGHT...THE LOW LEVEL FLOW WILL SHIFT TO A DRYING DOWNSLOPE WIND BY MONDAY MORNING...AND FOR THIS REASON WILL KEEP TOMORROW'S FORECAST DRY. LONG TERM (TUESDAY THROUGH SATURDAY)... A RETURN OF SOUTHERLY FLOW WILL ALLOW MOISTURE TO GRADUALLY INCREASE ACROSS THE AREA BEGINNING TUESDAY. HOWEVER...LACK OF AN IDENTIFIABLE SOURCE OF LIFT WILL PRECLUDE A POP MENTION FOR TUESDAY. LATER IN THE WEEK...THE UPPER FLOW WILL TRANSITION FROM ZONAL TO SOUTHWESTERLY... AS UPPER RIDGE BUILDS OVER THE DEEP SOUTH. THIS WILL SIGNAL A RETURN OF WEATHER MORE TYPICAL OF LATE SUMMER. THE CURRENT EXTENDED FORECAST HAS THIS WELL IN HAND. AVIATION... COPIOUS LOW LEVEL MOISTURE COMBINED WITH NELY SFC FLOW AND UPSLOPE LOW LEVEL FLOW HAVE PRODUCED STRATOCU VARYING FROM LOW VFR TO IFR ACROSS THE CWFA. SHRA DEVELOPING IN THIS FLOW AS WELL. EXPECT ALL TAF SITES TO HAVE IFR CIGS BEFORE DAYBREAK AS THE FLOW CONTINUES INTO THE MORNING. MVFR FOG SHOULD DEVELOP AS WELL. XCPT FOR KAVL WHERE FOG MORE LIKELY...IFR VSBY POSSIBLE WHERE HEAVIER SHOWERS MOVE OVER AN AIRFIELD...BUT THESE WILL BE TEMPORARY. HAVE ONLY INCLUDED VCSH AT KCLT THIS MORNING...BUT KGSP COULD BE AFFECTED AS WELL. CIGS SHOULD RISE AFTER DAYBREAK BECOMING MVFR AROUND 15Z AND VFR AROUND 18Z. WITH THE LOW LEVEL MOISTURE REMAINING ATMOS BECOMES UNSTABLE THIS AFTERNOON. CONVECTION MOST LIKELY OVER THE MTNS AND INCLUDED VCSH AT KAVL...BUT MAY NEED TO BE VCTS. LOW LEVEL MOISTURE AND UPSLOPE FLOW DIMINISH AFTER 00Z SO VFR CONDITIONS THRU THE EVENING. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SHORT TERM (UPDATE)...JAT sc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 859 AM EDT SUN AUG 15 2004 .SHORT TERM (REST OF TODAY)... SURFACE FRONT LOCATED OVER SC MIDLANDS THIS MORNING. ISENTROPIC LIFT OVER THIS BOUNDARY PRODUCING CLOUDS AND PRECIP ACROSS MUCH OF LEE THIS MORNING...AND HAVE CONTINUED THIS TREND THROUGH THE MORNING HOURS. INCREASED CLOUD COVER MUCH OF DAY...AND LOWERED TEMPERATURES ABOUT 1 DEGREE...2 IN FAR S. UPDATED WITH RUC WINDS...THOUGH STILL NE. EXPECT AFTERNOON CONVECTION TO BE BEST IN MOUNTAINS WHERE LESS CLOUD COVER EXISTS. INCREASD POPS TO CHANCE E PORTION THIS AFTERNOON TO ACOUNT FOR ACTIVITY CLOSER TO BOUNDARY AND BETTER MOISTURE...AND FOR BETTER MATCH WITH NEIGHBORING OFFICES. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 335 AM EDT SUN AUG 15 2004 SHORT TERM (TODAY THROUGH MONDAY NIGHT)... WV IMAGERY INDICATES THAT THE BACK EDGE OF THE DEEP MOISTURE STILL LINGERS OVER THE EXTREME EASTERN PORTION OF THE CWFA. SURFACE BOUNDARY REMAINS STALLED FROM THE MIDLANDS INTO THE NC COASTAL PLAIN. UPGLIDE OVER THIS FEATURE COMBINED WITH WEAK UPSLOPE FLOW AND ABUNDANT LOW LEVEL MOISTURE IS RESULTING IN WIDESPREAD LOW CLOUDS ACROSS THE AREA. IN ADDITION...AN AREA OF SHOWERS THAT DEVELOPED EARLIER IN THE UPGLIDE/DEEP MOISTURE REGIME ACROSS THE MIDLANDS WILL CLIP THE EXTREME SOUTHEAST CORNER OF OUR AREA THIS MORNING. WE'RE EVEN SEEING SOME SHOWERS DEVELOP IN THE DRIER AIR ACROSS THE UPSTATE. WE WILL GO AHEAD AND INCLUDE A CHANCE POP FOR THIS MORNING...ROUGHLY SOUTH OF I-40...AND FROM I-26 EAST TO HANDLE THIS ACTIVITY. THE DEEP MOISTURE WILL FINALLY BE SHUNTED EAST OF THE AREA BY LATE IN THE MORNING...AND UPGLIDE FLOW WILL WEAKEN AS THE BOUNDARY BEGINS TO WASH OUT. HOWEVER...A WEAK UPSLOPE COMPONENT WILL BE MAINTAINED THROUGH MOST OF THE DAY. IN ADDITION...THE AREA WILL REMAIN UNDER THE INFLUENCE OF THE RRQ OF AN UPPER JET STREAK. THEREFORE...A LOW CHANCE POP IS PROBABLY WARRANTED ACROSS THE HIGHER TERRAIN AND NC FOOTHILLS THIS PM. HAVE TAPERED POPS DOWN TO SLIGHT CHANCE ACROSS THE NC MNTNS/FHILLS AFTER EARLY EVENING. HOWEVER...THE UPPER TROUGH WILL MOVE OVER THE AREA TONIGHT...POSSIBLY ALLOWING SOME CONVECTION TO LINGER INTO THE OVERNIGHT HOURS. AS THE TROUGH SWINGS OVER THE AREA TONIGHT...THE LOW LEVEL FLOW WILL SHIFT TO A DRYING DOWNSLOPE WIND BY MONDAY MORNING...AND FOR THIS REASON WILL KEEP TOMORROW'S FORECAST DRY. LONG TERM (TUESDAY THROUGH SATURDAY)... A RETURN OF SOUTHERLY FLOW WILL ALLOW MOISTURE TO GRADUALLY INCREASE ACROSS THE AREA BEGINNING TUESDAY. HOWEVER...LACK OF AN IDENTIFIABLE SOURCE OF LIFT WILL PRECLUDE A POP MENTION FOR TUESDAY. LATER IN THE WEEK...THE UPPER FLOW WILL TRANSITION FROM ZONAL TO SOUTHWESTERLY... AS UPPER RIDGE BUILDS OVER THE DEEP SOUTH. THIS WILL SIGNAL A RETURN OF WEATHER MORE TYPICAL OF LATE SUMMER. THE CURRENT EXTENDED FORECAST HAS THIS WELL IN HAND. AVIATION... COPIOUS LOW LEVEL MOISTURE COMBINED WITH NELY SFC FLOW AND UPSLOPE LOW LEVEL FLOW HAVE PRODUCED STRATOCU VARYING FROM LOW VFR TO IFR ACROSS THE CWFA. SHRA DEVELOPING IN THIS FLOW AS WELL. EXPECT ALL TAF SITES TO HAVE IFR CIGS BEFORE DAYBREAK AS THE FLOW CONTINUES INTO THE MORNING. MVFR FOG SHOULD DEVELOP AS WELL. XCPT FOR KAVL WHERE FOG MORE LIKELY...IFR VSBY POSSIBLE WHERE HEAVIER SHOWERS MOVE OVER AN AIRFIELD...BUT THESE WILL BE TEMPORARY. HAVE ONLY INCLUDED VCSH AT KCLT THIS MORNING...BUT KGSP COULD BE AFFECTED AS WELL. CIGS SHOULD RISE AFTER DAYBREAK BECOMING MVFR AROUND 15Z AND VFR AROUND 18Z. WITH THE LOW LEVEL MOISTURE REMAINING ATMOS BECOMES UNSTABLE THIS AFTERNOON. CONVECTION MOST LIKELY OVER THE MTNS AND INCLUDED VCSH AT KAVL...BUT MAY NEED TO BE VCTS. LOW LEVEL MOISTURE AND UPSLOPE FLOW DIMINISH AFTER 00Z SO VFR CONDITIONS THRU THE EVENING. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SHORT TERM (UPDATE)...JAT sc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SAN ANGELO TX 855 PM CDT SUN AUG 15 2004 .UPDATE... LIGHTNING JUST ABOUT GONE FROM THE BIG COUNTRY AT THIS POINT... ALTHOUGH SHOWERS CONTINUE. TREND OF THE COVERAGE HAS BEEN DOWN OVER THE LAST HOUR OR SO...AND EXPECT THE TREND TO CONTINUE. STILL...AS WE HAVE SEEN THE PREVIOUS FEW NIGHTS...SCATTERED SHOWERS AND A FEW STORMS WILL LIKELY CONTINUE THROUGH THE OVERNIGHT HOURS AND WILL NEED TO CONTINUE CHANCE POPS. MORE ISOLATED ACTIVITY STILL ALSO ONGOING ACROSS PORTIONS OF THE CONCHO VALLEY AS WELL AND WILL NEED TO CONTINUE SLIGHT CHANCE POPS DOWN HERE AS WELL. UPDATED GRIDS AND TEXT PRODUCTS OUT SHORTLY. && .PREV DISCUSSION... QUICK UPDATE...AS CONVECTION CONTINUES TO BLOSSOM ALONG AND NORTH OF AN OUTFLOW BOUNDARY ACROSS THE BIG COUNTRY. INCREASED POPS UP THERE QUITE A BIT AND ADDED A MENTION OF LOCALLY HEAVY RAINFALL...AS 1 TO 2 INCH PER HOUR RAINFALL RATES HAVE BEEN INDICATED BY RADAR. AT FIRST GLANCE...THINK THIS AREA OF CONVECTION WILL PERSIST FOR THE NEXT FEW HOURS BEFORE BECOMING A LITTLE MORE SCATTERED AFTER SUNSET. LATEST SATELLITE AND WSR-88D DATA INDICATING SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS THE BIG COUNTRY...MAINLY NORTH OF INTERSTATE 20...AND ACROSS THE CONCHO VALLEY. LATEST RUC SUGGESTS A SHEAR AXIS OR DEFORMATION ZONE AT 700 MB IS DRIVING CURRENT SHOWER AND THUNDERSTORM DEVELOPMENT. MODELS CONTINUE THIS SHEAR AXIS OVER MUCH OF WEST CENTRAL THROUGH TONIGHT. HOWEVER...BASED ON POOR POP PERFORMANCE FOR THE LAST COUPLE RUNS...BELIEVE CONSERVATIVE POPS FOR TONIGHT WILL BE BEST APPROACH. YES...SOME AREAS ACROSS WEST CENTRAL TEXAS WILL RECEIVE MEASURABLE PRECIPITATION...ESPECIALLY ACROSS THE BIG COUNTRY. YET...BELIEVE 40 OR 50 POPS UNWISE. THUS...WILL GO WITH 30 POPS FOR THE BIG COUNTRY AND AND 20S ELSEWHERE FOR TONIGHT. FOR TOMORROW THROUGH THE MIDDLE OF THE WEEK...POPS LOOK VERY LOW. THUS... 10 POPS FOR THE CCF WITH NO MENTION IN THE ZONES LOOKS BEST. MOSTLY CLOUDY SKIES WILL DOMINATE WEST CENTRAL TEXAS TONIGHT. THEN...EXPECT PARTLY CLOUDY SKIES THROUGH MID WEEK. NUMBERS CLOSE TO MAV MOST LOOK GOOD. MODELS CONTINUE TO BRING A WEEK COLD FRONT DEEP INTO WEST CENTRAL TEXAS ON FRIDAY...WHICH RETREATS QUICKLY NORTH FRIDAY NIGHT... BEFORE ATTEMPTING ANOTHER PUSH INTO THE BIG COUNTRY ON SATURDAY. NORTHWEST TO WEST FLOW ALOFT CONTINUES INTO NEXT WEEKEND WITH THE MODELS SUGGESTING A FEW EMBEDDED SHORTWAVES WILL MOVE OVER WEST CENTRAL TEXAS DURING THAT TIME. FOR NOW...WILL CONTINUE 20 POPS MAINLY FOR THE BIG COUNTRY WHERE BETTER UPPER-LEVEL DYNAMICS WILL BE CLOSER. OTHERWISE...APPEARS A MORE SUMMER-LIKE PATTERN WILL DOMINATE WEST CENTRAL TEXAS FROM MID WEEK THROUGH NEXT WEEKEND... WITH AFTERNOON HIGHS BACK INTO THE MID AND UPPER 90S. && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SAN ANGELO TX 442 PM CDT SUN AUG 15 2004 .UPDATE... QUICK UPDATE...AS CONVECTION CONTINUES TO BLOSSOM ALONG AND NORTH OF AN OUTFLOW BOUNDARY ACROSS THE BIG COUNTRY. INCREASED POPS UP THERE QUITE A BIT AND ADDED A MENTION OF LOCALLY HEAVY RAINFALL...AS 1 TO 2 INCH PER HOUR RAINFALL RATES HAVE BEEN INDICATED BY RADAR. AT FIRST GLANCE...THINK THIS AREA OF CONVECTION WILL PERSIST FOR THE NEXT FEW HOURS BEFORE BECOMING A LITTLE MORE SCATTERED AFTER SUNSET. && .PREV DISCUSSION... LATEST SATELLITE AND WSR-88D DATA INDICATING SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS THE BIG COUNTRY...MAINLY NORTH OF INTERSTATE 20...AND ACROSS THE CONCHO VALLEY. LATEST RUC SUGGESTS A SHEAR AXIS OR DEFORMATION ZONE AT 700 MB IS DRIVING CURRENT SHOWER AND THUNDERSTORM DEVELOPMENT. MODELS CONTINUE THIS SHEAR AXIS OVER MUCH OF WEST CENTRAL THROUGH TONIGHT. HOWEVER...BASED ON POOR POP PERFORMANCE FOR THE LAST COUPLE RUNS...BELIEVE CONSERVATIVE POPS FOR TONIGHT WILL BE BEST APPROACH. YES...SOME AREAS ACROSS WEST CENTRAL TEXAS WILL RECEIVE MEASURABLE PRECIPITATION...ESPECIALLY ACROSS THE BIG COUNTRY. YET...BELIEVE 40 OR 50 POPS UNWISE. THUS...WILL GO WITH 30 POPS FOR THE BIG COUNTRY AND AND 20S ELSEWHERE FOR TONIGHT. FOR TOMORROW THROUGH THE MIDDLE OF THE WEEK...POPS LOOK VERY LOW. THUS... 10 POPS FOR THE CCF WITH NO MENTION IN THE ZONES LOOKS BEST. MOSTLY CLOUDY SKIES WILL DOMINATE WEST CENTRAL TEXAS TONIGHT. THEN...EXPECT PARTLY CLOUDY SKIES THROUGH MID WEEK. NUMBERS CLOSE TO MAV MOST LOOK GOOD. MODELS CONTINUE TO BRING A WEEK COLD FRONT DEEP INTO WEST CENTRAL TEXAS ON FRIDAY...WHICH RETREATS QUICKLY NORTH FRIDAY NIGHT... BEFORE ATTEMPTING ANOTHER PUSH INTO THE BIG COUNTRY ON SATURDAY. NORTHWEST TO WEST FLOW ALOFT CONTINUES INTO NEXT WEEKEND WITH THE MODELS SUGGESTING A FEW EMBEDDED SHORTWAVES WILL MOVE OVER WEST CENTRAL TEXAS DURING THAT TIME. FOR NOW...WILL CONTINUE 20 POPS MAINLY FOR THE BIG COUNTRY WHERE BETTER UPPER-LEVEL DYNAMICS WILL BE CLOSER. OTHERWISE...APPEARS A MORE SUMMER-LIKE PATTERN WILL DOMINATE WEST CENTRAL TEXAS FROM MID WEEK THROUGH NEXT WEEKEND... WITH AFTERNOON HIGHS BACK INTO THE MID AND UPPER 90S. && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 310 PM CDT SUN AUG 15 2004 .SHORT TERM... LATEST SATELLITE AND WSR-88D DATA INDICATING SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS THE BIG COUNTRY...MAINLY NORTH OF INTERSTATE 20...AND ACROSS THE CONCHO VALLEY. LATEST RUC SUGGESTS A SHEAR AXIS OR DEFORMATION ZONE AT 700 MB IS DRIVING CURRENT SHOWER AND THUNDERSTORM DEVELOPMENT. MODELS CONTINUE THIS SHEAR AXIS OVER MUCH OF WEST CENTRAL THROUGH TONIGHT. HOWEVER...BASED ON POOR POP PERFORMANCE FOR THE LAST COUPLE RUNS...BELIEVE CONSERVATIVE POPS FOR TONIGHT WILL BE BEST APPROACH. YES...SOME AREAS ACROSS WEST CENTRAL TEXAS WILL RECEIVE MEASURABLE PRECIPITATION...ESPECIALLY ACROSS THE BIG COUNTRY. YET...BELIEVE 40 OR 50 POPS UNWISE. THUS...WILL GO WITH 30 POPS FOR THE BIG COUNTRY AND AND 20S ELSEWHERE FOR TONIGHT. FOR TOMORROW THROUGH THE MIDDLE OF THE WEEK...POPS LOOK VERY LOW. THUS... 10 POPS FOR THE CCF WITH NO MENTION IN THE ZONES LOOKS BEST. MOSTLY CLOUDY SKIES WILL DOMINATE WEST CENTRAL TEXAS TONIGHT. THEN...EXPECT PARTLY CLOUDY SKIES THROUGH MID WEEK. NUMBERS CLOSE TO MAV MOST LOOK GOOD. && .LONG TERM... MODELS CONTINUE TO BRING A WEEK COLD FRONT DEEP INTO WEST CENTRAL TEXAS ON FRIDAY...WHICH RETREATS QUICKLY NORTH FRIDAY NIGHT... BEFORE ATTEMPTING ANOTHER PUSH INTO THE BIG COUNTRY ON SATURDAY. NORTHWEST TO WEST FLOW ALOFT CONTINUES INTO NEXT WEEKEND WITH THE MODELS SUGGESTING A FEW EMBEDDED SHORTWAVES WILL MOVE OVER WEST CENTRAL TEXAS DURING THAT TIME. FOR NOW...WILL CONTINUE 20 POPS MAINLY FOR THE BIG COUNTRY WHERE BETTER UPPER-LEVEL DYNAMICS WILL BE CLOSER. OTHERWISE...APPEARS A MORE SUMMER-LIKE PATTERN WILL DOMINATE WEST CENTRAL TEXAS FROM MID WEEK THROUGH NEXT WEEKEND... WITH AFTERNOON HIGHS BACK INTO THE MID AND UPPER 90S. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 65 86 66 90 / 30 10 10 10 SAN ANGELO 65 88 65 91 / 20 10 10 10 JUNCTION 64 89 64 90 / 20 10 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/HUBER tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 1230 PM CDT SUN AUG 15 2004 .AVIATION DISCUSSION... CURRENT KFWS 88D DATA SHOWING RW/EMBEDDED TRW MAINLY CONFINED TO NW PORTIONS OF KDFW TRACON...WITH MOST CONCENTRATED AREA ALONG AND NW OF A LINE FROM KMWL-KLUD-KGLE. RUC/MESOETA GUIDANCE IS IN AGREEMENT ON WEAKENING THIS ACTIVITY THROUGH THE AFTERNOON...AS WEAK UPPER LEVEL SPEED MAX AND ASSOCIATED MID-LEVEL VORT MAX MOVE EWD INTO ARKANSAS. THUS...WILL NOT INCLUDE A MENTION OF PRECIP IN THE TAFS ATTM. SCT TO BKN VFR CIGS WILL PERSIST ACROSS THE KDFW/KACT TRACONS THROUGHOUT THE FORECAST PERIOD...WITH BASES GENERALLY 7-10 KFT. CIRRUS DEBRIS CLOUDINESS WILL ALSO BE POSSIBLE THROUGH THIS EVENING. SFC WINDS WILL REMAIN 160-200 THROUGH THE PERIOD...WITH SPEEDS AOB 12 KTS. 65/DD && .UPDATE... WILL MAKE SOME MINOR ADJUSTMENTS TO CLOUDS AND WEATHER PRIMARILY THIS AFTERNOON THROUGH MONDAY. CURRENT FORECAST APPEARS ON TRACK SO WILL NOT MAKE ANY SIGNIFICANT CHANGES AT THIS POINT. 42 && .DISCUSSION... THE NORTHWESTERLY FLOW ALOFT THAT WE HAVE SEEN FOR THE LAST FEW DAYS IS FORECAST TO WEAKEN AFTER MONDAY. THIS WILL RESULT IN LOWERED RAIN CHANCES AND WARMER...BUT STILL BELOW NORMAL TEMPERATURES FOR THE FOR THE BEGINNING OF THE WORK WEEK. IT STILL LOOKS LIKE WE WILL SEE ANOTHER FRONT COME DOWN FRIDAY AS A DECENT SHORTWAVE MOVE ACROSS THE SOUTHERN PLAINS. THUS HAVE KEPT LOW POPS THURSDAY... WITH BETTER CHANCES THURSDAY NIGHT AND FRIDAY. #58 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 88 68 90 70 / 30 20 10 0 WACO, TX 90 67 92 68 / 20 10 10 10 PARIS, TX 85 63 88 65 / 20 20 10 10 DENTON, TX 85 67 90 69 / 30 20 10 10 MCKINNEY, TX 86 66 90 69 / 30 20 10 10 DALLAS, TX 88 68 90 71 / 30 10 10 0 TERRELL, TX 87 66 91 69 / 20 10 10 0 CORSICANA, TX 88 66 91 69 / 20 10 10 0 TEMPLE, TX 90 66 92 68 / 20 10 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... TX...NONE. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 1003 AM CDT SUN AUG 15 2004 .SHORT-TERM (REST OF TODAY)...500HPA SHORTWAVE OVER MEXICO WILL MOVE EAST TODAY. MODELS WEAKEN THIS FEATURE BUT SATELLITE IMAGERY SUGGESTS OTHERWISE. SOME MID/UPPER-LEVEL CLOUDINESS IS STILL EXPECTED(MAINLY THE WEST). CUMULUS FIELD IS NOT EXPECTED TO BE AS PRONOUNCED AS YESTERDAY WITH LOW-LEVEL MOISTURE/INSTABILITY LESS. WILL MAINTAIN THE PARTLY CLOUDY SKY COVER BUT PORTIONS OF THE EAST WILL BE CLOSE TO MOSTLY SUNNY. LATEST RUC SHOWS A 25 KNOT 850HPA JETMAX MOVING OVER THE WATERS TOWARD 00Z. OTHER MODELS DO NOT INDICATE THIS AND IS ACCEPTED GIVEN THE LACK OF A DRY AIR INTRUSION OVER THE GLFMEX WHICH OCCURRED YESTERDAY BEHIND THE NOSE OF A 850HPA JETMAX. WILL INDICATE WIND SPEEDS AROUND THE HIGH END OF CURRENT RANGES FROM THE COASTAL COUNTIES AND POINTS EAST. WILL ALSO INITIALIZE WITH A NORTHEAST WIND OVER EASTERN PORTIONS GIVEN CURRENT OBSERVATIONS. TEMPERATURES SHOULD DUPLICATE YESTERDAY/S VALUES BUT LAREDO MAY NOT BE QUITE AS HOT GIVEN THE ADDITIONAL CLOUD COVER AS COMPARED TO YESTERDAY. && .CRP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ 85/SHORT-TERM tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 230 AM EDT MON AUG 16 2004 .SHORT TERM...AS PREVIOUS SHIFT STATED...H2O VAPOR LOOP & RUC SHOW NEARLY ZONAL FLOW ACROSS THE AREA AS E U.S. TROF FILLS. WK ANTICYCLONE CENTERED OVER S FL. SOMEWHAT DRIER AIR ALOFT OVER THE NW GOMEX UPSTREAM FROM OUR CWA (COUNTY WARNING AREA). REMAINS OF SUNDAY'S VORT MAX FIRING OFF TSTMS OVER THE ATLC COASTAL WATERS... MAINLY NEAR THE GULF STREAM. AT THE SFC...WK FRONTAL BOUNDARY CONTINUES TO BECOME MORE DIFFUSE...BUT STILL APPEARS TO BE SOME CONVERGENCE ALONG THIS BOUNDARY. MOS POPS SIMILAR TODAY AS MUCH OF THE DYNAMIC FORCING DEPARTS THE AREA LEAVING WK CONVERGENCE ALONG THE FRONTAL BOUNDARY AND SEABREEZE CIRCULATIONS IN A VERY LIGHT LOW-LEVEL FLOW REGIME. HAVE THEREFORE GONE WITH GENERALLY LOW CHANCE POPS ACROSS THE AREA. HAVE INDICATED EARLIEST POPS OVER SE ZONES AS SOME EARLY ONSHORE LOW-LEVEL FLOW MAY HELP CONVECTION BUILD BACK TOWARD THE FLAGLER AND ST. JOHNS COUNTY COASTS. MOS POPS DIVERGE FOR TUE AS ETA SUITE APPEARS TO BUILD A WK UPPER HIGH OVER GA ZONES WITH ASSOCIATED SUBSIDENCE AND DRYING. THINK THIS IS OVERDONE...BUT LIKE THE GENERAL DISTRIBUTION OF POPS FROM THE ETA...SO WILL TWEAK THESE NUMBERS UPWARDS. BESIDES POPS...ONLY OTHER CONCERN IS LATE NIGHT FOG. LOW-LEVEL MOISTURE AND LIGHT LOW-LEVEL FLOW WILL PROMOTE PATCHY FOG. WON'T INCLUDE THIS PAST THE 2ND PERIOD DUE TO THE UNCERTAINTY. .LONG TERM...NEAR CLIMO WX AS BERMUDA HIGH HOLDS UNTIL LATE IN THE WEEKEND WHEN A WEAK FRONT APPROACHES FROM THE NW. NO CHANGES. && .MARINE...WITH THE WEAK PRESSURE GRADIENT OVER THE AREA...HAVE LEANED TOWARDS THE MESO-ETA WHICH HAS A BETTER HANDLE ON THE SEABREEZES AND MESOSCALE FEATURES. WINDS NEXT FEW DAYS LIGHT...EXCEPT INCREASING IN THE AFTERNOON ALONG EAST COAST AS SEABREEZE MOVES IN. SEAS GENERALLY 2 TO 3 FEET. && .PRELIMINARY POINT TEMPS/POPS... AMG 89 70 91 70 / 30 10 30 30 SSI 86 73 86 74 / 30 10 30 20 JAX 89 71 88 71 / 40 20 30 20 SGJ 86 73 86 73 / 40 20 30 20 GNV 89 71 90 71 / 40 30 50 50 OCF 89 71 91 71 / 50 30 50 40 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. && $$ CARROLL/PETERSON fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 330 AM EDT SUN AUG 15 2004 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW PERSISTENT MEAN TROF OVER ERN NAMERICA DOWNSTREAM OF WRN RDG. FA REMAINS UNDER INFLUENCE OF SHRTWV RDG/DRY AIRMASS DEPICTED ON 00Z GRB/APX SDNGS EARLY THIS MRNG...BUT A HEALTHY SHRTWV NOTED JUST S OF LK WINNIPEG DIGGING SSE. COMPOSITE 88DS SHOW MAJORITY OF PCPN ASSOCIATED WITH THIS SYS FM ERN ND SE INTO SW MN IN ADVANCE OF A NNW-SEE ORIENTED H85 WARM FNT IN THE DAKOTAS. AREA OF ECHO SHOWING ONLY A SLOW EWD MVMNT. IN FACT...CELLS IN THE ERN DAKOTAS TENDING TO MOVE MORE SSE THAN E. BEHIND THE SHRTWV...CYQD SDNG SHOWS A MUCH DRIER/STABLE AIRMASS (KINX 4) EVEN THOUGH LLVL AIR NOT MUCH COOLER/DRIER (SFC DWPTS REMAIN IN THE 55 TO 60 RANGE). MAIN FCST CONCERNS THIS PACKAGE ARE PCPN CHCS TDAY INTO TUE...THEN TIMING/IMPACT OF MORE SGNFT COLD FROPA FCST ON WED ASSOCIATED WITH NEXT SHRTWV DROPPING SEWD INTO ERN TROF. TDAY/TNGT...MODELS SHOW LK WINNIPEG SHRTWV DROPPING SEWD INTO WI BY 00Z AND THEN INTO LWR MI BY 12Z TUE. AS HAS BEEN THE CASE THE LAST COUPLE OF MODEL RUNS...THE MOST VIGOROUS DPVA/DEEP LYR QVECTOR CNVGC/H85 THETA-E ADVCTN/H7 UVV/MODEL SIMULATED CNVCTN PROGGED TO TRACK S OF THE FA. OBSVD RADAR/STLT TRENDS APPEAR TO SUPPORT THIS FCST SCENARIO. HOWEVER... THERE HAS BEEN A TREND FOR BETTER H85 THETA-E ADVCTN/H85-5 QVECTOR CNVGC/H7 UVV TO DVLP INTO THE ERN ZNS IN ADVANCE OF SHRTWV MON NGT. WL RETAIN THE 50 POP NR THE WI BORDER TDAY BUT KEEP PCPN OUT OF THE FCST E OF MQT-MNM. THEN WL HIT PCPN CHCS A LITTLE HARDER ACRS THE CNTRL/E TNGT BY BUMPING POPS UP TO 50 MORE IN LINE WITH MODEL MOS FCSTS. STILL EXPECT PCPN TO END LATE TNGT ACRS THE FAR W FOLLOWING PASSAGE OF MID LVL TROF AXIS AND ARRIVAL OF NVA/DEEP LYR QVECTOR DVGC/DRIER AIR DEPICTED ON 00Z CYQD SDNG. INTRODUCED PTCHY FOG IN AREAS THAT EXPERIENCE MID LVL DRYING ABV LINGERING LLVL MSTR OVRNGT. ETA/GFS FCST LINX/SSI RELATED TO PASSAGE OF BEST MID LVL COOLING TO THE S AND DRY ANTECEDENT AIRMASS TDAY N OF H85 WARM FNT AS WELL AS ETA/GFS MOS TSRA CHCS STILL SUPPORT KEEPING TSRA OUT OF FCST TDAY/ TNGT. HIEST TMAX TDAY ACRS THE ERN ZNS WHERE CLDS WL THICKEN LATER...BUT SLY FLOW OFF LK MI WL MODERATE TEMPS. MID LVL DRYING (AIRMASS FM CQYD) CONTINUES E BEHIND DEPARTING MID LVL TROF AXIS TUE MRNG WITH ARRIVAL OF DNVA/DEEP LYR QVECTOR DVGC/ STRENGTHENING MID LVL SUBSIDENCE INVRN. THIS PROCESS IS INTERRUPTED A BIT IN THE GFS FCST WITH ARRIVAL OF WHAT APPEARS TO BE CONVECTIVELY ENHANCED SHRTWV. THIS SYS NOW OVER EXTREME SW CAN...AND PREFER ETA FCST OF THIS SHRTWV MOVING WELL S OF FA AND BEING WEAKER. ETA FCST SDNGS HOWEVER SHOW CONSIDERABLE SBCAPE DVLPG DURING THE DAY UNDER THE MID LVL DRYING/DEPARTING CLDS. MODEL SHOWS CAPES INCRSG TO AS HI AS 1500 J/KG...BUT FCST SFC DWPTS APRCHG 65 SEEM UNREALISTIC. MODIFICATION OF ETA FCST SDNGS FOR SFC DWPT IN THE 55 TO 60 RANGE (AS OBSVD BEHIND TROF THIS MRNG) RESULTS IN CAPES 300-500 J/KG LOWER THAN EXPLICIT MODEL FCST. SINCE ETA DOES NOT GENERATE QPF DURING THE AFTN OVER FA EVEN WITH HI MODEL DVLPD INSTABILITY (GFS DOES GENERATE QPF)...BELIEVE MID LVL DRYING/STABILIZATION WL DOMINATE AND PREVENT SHRA/TSRA. HOWEVER AS DAYSHIFT POINTED OUT...INCRSG INSOLATION THAT CAUSES TMAX TO APRCH HI END OF MOS FCST TEMPS PER DEEP MIXING THRU PBL ON ETA FCST SDNGS/FLAT PRES GRADIENT WL RESULT IN LK BREEZE FORMATION. SINCE MOS FCSTS INDICATE CHC POPS ALMOST EVERYWHERE TUE AFTN...CONFIDENCE NOT HI ENUF TO REMOVE GOING SHRA/TSRA CHCS FM FCST OVER ERN ZNS WHERE POTENTIAL LK BREEZE CNVGC BTWN SUP/MI BNDRYS MIGHT COUNTER NEGATIVE MID LVL PROCESSES THAT DON'T ARRIVE IN FULL FORCE IN THAT PART OF THE CWA UNTIL THE AFTN. SHRA OVER THE ERN CWA WL DSPT QUICKLY LATE TUE AFTN WITH WANING INSOLATION UNDER MID LVL DRYING. TUE NGT SHUD BE ON THE TRANQUIL SIDE WITH DNVA/DEEP QVECTOR DVGC/SUBSIDENCE/ARRIVAL OF WEAK HI PRES RDG. SINCE GFS RETAINS DVLPG WAD/DESTABILIZATION (SSI FALLING AOB ZERO) OVER NW LK SUP TOWARD 12Z WED IN ADVANCE OF POTENT SHRWTV FCST TO ARRIVE NEAR LK WINNIPEG THEN...WL RETAIN LO CHC LATE NGT SHRA/ TSRA OVER THE KEWEENAW PENINSULA/ISLE ROYALE AND ADJOINING LK SUP EVEN THOUGH GFS DOES NOT GENERATE ANY PCPN (UKMET DOES). OTRW...FA WL BE CLR TO PCLDY WITH AN INCRSG SW FLOW RESTRICTING THE DIURNAL DCRS IN TEMP AT LEAST OVER THE NW HALF OF FA. LOWER TMINS AOB MOS GUIDANCE OVER THE INTERIOR SCNTRL/E WHERE PRES GRADIENT DOES NOT TIGHTEN TOO MUCH BEFORE 12Z. GFS/UKMET/ETA IN GOOD AGREEMENT ON DRIVING STRG SFC COLD FNT ACRS THE FA AND INTO NRN LK MI BY 00Z THU (CNDN MODEL A BIT SLOWER) AS POTENT SHRTWV NR LK WINNIPEG AT 12Z WED MOVES ACRS ONTARIO. DESPITE STRENGTH OF FNT AND POTENTIAL FOR CONSIDERABLE HTG OF LLVLS WITH FROPA AT DIURNAL MAX/MSTR CNVGC/ FRONTOGENETIC ENHANCEMENT... ETA SHOWS LINX TO -5C/H85 TEMP RISING NR 16C (UKMET/GFS A BIT MORE CONSERVATIVE WITH 14C)...WL NOT INCRS GOING CHC POPS DUE TO FCST LOCATION OF FA IN RIGHT EXIT OF SUPPORTING H3 JET MAX. GFS/ETA MOS POPS SUPPORT THIS FCST. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 348 AM CDT MON AUG 16 2004 .DISCUSSION... A COUPLE OF WEAK UPPER LEVEL DISTURBANCES WERE NOTED ON WATER VAPOR IMAGERY EARLY THIS MORNING. THE FIRST WAS TRACKING SOUTHWESTWARD ACROSS SOUTHERN NEBRASKA WHILE THE SECOND WAS FOUND OVER EASTERN OKLAHOMA. SHOWERS AND THUNDERSTORMS HAD DEVELOPED WITH BOTH OF THESE FEATURES. WAA/ISENTROPIC LIFT THUNDERSTORMS WERE FOUND OVER CENTRAL KANSAS AS 35KT WINDS AT 850 MB NOSED INTO THAT AREA. MAIN SHORT TERM FORECAST DILEMMA WILL BE IF PARTS OF THE AREA WILL GET CONVECTION TODAY. THE RUC INDICATES THE LOW-LEVEL JET TO THE WEST WILL VEER TOWARDS DAWN...ALLOWING MOISTURE TO INCREASE ACROSS EASTERN KANSAS AND WESTERN MISSOURI. THE ETA ALSO SHOWS A SIMILAR PATTERN...AND BOTH THE 00Z AND 06Z RUNS SHOW A WEAK BULLSEYE OF 925-850MB LAYER THETA-E CONVERGENCE THIS MORNING THROUGH EARLY AFTERNOON. IN ADDITION...ETA 0-1KM MLCAPE VALUES INCREASE TO AROUND 1000 J/KG TO THE WEST OF SPRINGFIELD. NONE OF THE MODEL QPFS PRODUCE ANY PRECIPITATION ACROSS THE AREA TODAY. HOWEVER I CAN'T IGNORE THE AFOREMENTIONED LOW-LEVEL THETA-E CONVERGENCE...SO I WILL BE ADDING SOME SLIGHT POPS ACROSS THE WESTERN HALF OF THE FORECAST AREA TODAY. HAVE NOT CHANGED THE GOING POP GRIDS DURING THE TONIGHT(MONDAY NIGHT) THROUGH WEDNESDAY NIGHT PERIOD. MAINLY HAVE 30 POPS ACROSS THE NORTHERN THIRD OF THE AREA WITH VALUES TAPERING OFF TO THE SOUTH. THE ETA AND GFS BOTH SHOW A FRONT STALLING OUT TO THE NORTH OF THE FORECAST AREA BY TUESDAY MORNING. THE ETA PUTS THE FRONT ON THE DOORSTEP OF MY NORTHERN COUNTIES WHILE THE GFS IS FURTHER NORTH. EXPECT MCS ACTIVITY TO FIRE ALONG THE BOUNDARY EACH AFT/EVE AFFECTING LOCATIONS NORTH OF THE FORECAST AREA. HOWEVER...CORFIDI VECTORS INDICATE A SOUTHWARD MOVEMENT...WHICH MAY ALLOW SOME STORMS TO BRUSH NORTHERN LOCATIONS. FOR THE REMAINDER OF THE EXTENDED...THE GFS BRINGS THE FRONT FURTHER SOUTH INTO THE OZARKS REGION BY THURSDAY NIGHT AND LINGERS IT IN THE AREA THROUGH SATURDAY. THEREFORE KEPT THE BROAD-BRUSHED 30 POPS FOR THIS PERIOD. WOULD NOT BE SURPRISED IF LATER SHIFTS WILL NEED TO RAISE POPS AT SOME POINT DURING THIS PERIOD. TEMPERATURES THIS WEEK LOOK MUCH WARMER THAN THE PREVIOUS WEEK. TODAY'S HIGHS WILL WARM INTO THE LOWER 80S. THE MERCURY MAY WARM INTO THE MIDDLE AND UPPER 80S TUESDAY AND WEDNESDAY...DEPENDING ON HOW MUCH CLOUD COVER THE AREA RECEIVES FROM THE CONVECTION FIRING TO THE NORTH. && .AVIATION... EXPECT VFR CONDITIONS ACROSS THE AREA TODAY...AS SCATTERED TO BROKEN CUMULUS AROUND 5000 FEET DEVELOP. SOME ISOLATED CONVECTION IS POSSIBLE ACROSS SOUTHEAST KANSAS AND FAR WESTERN MISSOURI...HOWEVER THE LOW COVERAGE DOES NOT WARRANT INCLUSION IN THE UPCOMING AVIATION PRODUCTS. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ SAW mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 345 AM CDT MON AUG 16 2004 .DISCUSSION... ...POP FORECAST TODAY AND THROUGHOUT THE WEEK MAIN CONCERN... WATERVAPOR LOOP REVEALS SHORTWAVE OVER EASTERN DAKOTAS IN NW FLOW... WHILE 07Z SURFACE ANALYSIS SHOWS LOW JUST EAST OF PIERRE SOUTH DAKOTA. THIS WAVE TRIGGERED SMALL MCS CURRENTLY MOVING OUT OF SOUTH CENTRAL NEBRASKA AND INTO NORTH CENTRAL KANSAS. NO MODEL HANDLED THIS CONVECTIVE ACTIVITY WELL...ALTHOUGH RUC SEEMED TO EVENTUALLY SHOW SOME HINT. RUC HAS BEEN CONSISTENT IN DEVELOPING NEW CONVECTION SOMETIME THIS MORNING FROM NORTHEAST NEBRASKA INTO MINNESOTA...WHICH IS NOW BEING SUPPORTED BY NEW 06Z ETA. ETA AND GFS AND RUC IN FAIR AGREEMENT WITH TAKING THE SURFACE LOW INTO THE SOUTHEAST CORNER OF SOUTH DAKOTA LATE THIS AFTERNOON WITH FRONT PUSHING INTO EASTERN NEBRASKA...WHILE UPPER TROF MAGNIFIES. WITH CONVECTIVE TEMPERATURE EXPECTED TO BE REACHED BY MID AFTERNOON AND PLENTY OF VERTICAL MOTION FROM FRONT/DPVA...SCATTERED STORMS LOOK REASONABLE. ETA FORECAST SOUNDINGS REMOVE ALL CONVECTIVE INHIBITION THIS AFTERNOON...YET ETA STILL IS SLOW TO DEVELOP CONVECTION ALONG THE FRONT THIS AFTERNOON...WHICH LOOKS WAY UNDERDONE. HIGHER RESOLUTION 13 KM RUC QPF MUCH MORE LIBERAL WHICH LOOKS MORE REALISTIC. SEVERE THREAT COVERED WELL IN SWODY1...NOT WIDESPREAD BUT SOME STRONG UPDRAFTS EXPECTED WITH MARGINAL BULK SHEAR. RANGED POPS THIS AFTERNOON AND EVENING FROM 20S FAR NORTH TO 50S SOUTHEAST. FRONT MOVES SOUTH OF CWA TUESDAY MORNING WITH WEAK SURFACE HIGH AND SUBSIDENCE...BUT UNCERTAINTY EXISTS WITH BRINGING THE FRONT BACK INTO THE REGION TUESDAY NIGHT AND WHERE THE FRONT ENDS UP THROUGH THURSDAY. ETA HANGS IT UP ACROSS OAX SOUTHERN COUNTIES...BUT GFS KEEPS IT JUST SOUTH. BOTH MODELS BRING STRONG SHORTWAVE THROUGH EITHER LATE WEDNESDAY OR THURSDAY...AND FRONT SHOULD BE WELL DEFINED. KEPT CHANCE POPS GOING WEDNESDAY INTO THURSDAY WITH THESE FEATURES. THIS FRONT MAY CONTINUE TO BE A PLAYER INTO THE WEEKEND...BUT WILL HOLD OFF ON MAKING ADJUSTMENTS BEYOND THURSDAY. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ NIETFELD ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 245 AM CDT MON AUG 16 2004 .SYNOPSIS... DATA ANALYSIS AT 06Z SHOWING A MULTICELLULAR COMPLEX OF THUNDERSTORMS OVER MINNESOTA AND EASTERN SOUTH DAKOTA. THIS CONVECTION IS ALONG THE NOSE OF THE LOW LEVEL MOISTURE TRANSPORT/THERMODYNAMIC FORCING. AS THE STORMS MOVE EAST...THEY WEAKEN AS THEY LOSE THE FORCING TO SUPPORT AND ALSO ENTER A MORE STABLE ENVIRONMENT. SURFACE LOW PRESSURE WAS CENTERED IN NORTH-CENTRAL SOUTH DAKOTA. THIS WAS ALONG A COLD FRONT THAT EXTENDED FROM KGFK TO NEAR KVTN. THE PROGRESS OF THIS FRONT RESEMBLES THE SLOWER SOLUTIONS HAVE BEEN DISCUSSED OVER THE PAST FEW DAYS. WATER VAPOR AND 500 MB ANALYSIS SHOWS A LONGWAVE TROUGH OVER EASTERN NORTH AMERICA...A TROUGH OVER THE WESTERN PORTION AND A SIGNIFICANT CLOSED LOW CENTERED NEAR 45.6N 140.0W. THE FORECAST AREA REMAINS IN A NORTHWEST FLOW REGIME. WITHIN THE MEAN PATTERN...THERE IS A SIGNIFICANT DISTURBANCE MOVING SOUTHEAST THROUGH THE HIGH PLAINS. THE FORCING ASSOCIATED WITH THIS FEATURE IS AIDING IN THE CONVECTIVE DEVELOPMENT ALREADY MENTIONED. A SECOND SIGNIFICANT DISTURBANCE IS MOVING SOUTHEAST THROUGH CANADA. THIS FEATURE WAS A BIT MORE SHEARED...CENTERED OVER NORTHERN HUDSON BAY...WITH A STRONG SHEAR AXIS EXTENDING THROUGH THE NORTHERN PORTION OF THE SOUTHERN TERRITORIES. && .SHORT TERM...TONIGHT THROUGH WEDNESDAY FORECAST PROBLEMS...TIMING OF FRONTS MOVING THROUGH THE FORECAST AREA AND STRENGTH/DURATION OF ASSOCIATED CONVECTION. FORECASTER CONFIDENCE IS MEDIUM. GFS/ETA EXHIBITING ADDITIONAL CONSENSUS COMPARED TO PREVIOUS RUNS REGARDING THE TIMING OF THE FRONTAL PASSAGE. BOTH SHOW THE FRONT ENTERING THE FORECAST AREA AT 12Z TUESDAY...THEN EXITING BY 00Z WEDNESDAY. THE DIFFERENCE BETWEEN THESE MODELS IS THE EVOLUTION OF THE ONGOING CONVECTION. ETA STILL MOVES THE COMPLEX OF STORMS THROUGH THE FORECAST AREA TODAY. THE FRONTAL PASSAGE IS THEREFORE DRY WITH THE ETA. THE GFS CONTINUES CONVECTION TODAY WITH REDEVELOPMENT THIS EVENING AND AN ACTIVE FRONTAL PASSAGE AND MOVE CONVECTION BEHIND THE FRONT. THE FSL DEV RUC PRODUCES A SOLUTION THAT KEEPS THE CONVECTION GOING FOR MUCH OF THE DAY...WEST OF THE FORECAST AREA. THEN...IT RE-INTENSIFIES TONIGHT WITH THE DEVELOPMENT OF INCREASED LOW LEVEL THERMODYNAMIC FORCING...PRODUCING AN ACTIVE FRONTAL PASSAGE TUESDAY MORNING. CONVECTION END WITH THE FRONTAL PASSAGE. NONE OF THESE MODELS ARE REALLY HANDLING WHAT IS CURRENTLY HAPPENING ALL THAT WELL...AND THEIR SOLUTION TODAY IS NOT WHAT I WOULD EXPECT TO EVOLVE. THIS ALSO HOLDS TRUE TONIGHT AND TUESDAY. I EXPECT THE LOW LEVEL JET TO TURN GRADUALLY EAST. THIS WILL CAUSE THE ONGOING CONVECTION TO OVERSPREAD THE REMAINDER OF THE FORECAST AREA THIS MORNING. ALL 3 MODELS AGREE WITH THIS EVOLUTION OF THE LOW LEVEL JET. THE LOW LEVEL JET PERSISTS DURING THE DAY. THIS WOULD PROVIDE ENOUGH FORCING TO CONTINUE THE CONVECTION OVER THE FORECAST AREA TODAY ACROSS THE NORTHERN HALF. THEREFORE...HAVE MADE A SIGNIFICANT GRID ADJUSTMENT TO THE HIGH TEMPERATURE/PRECIPITATION/CLOUD GRIDS TO BE CONSISTENT WITH THIS THINKING. AS FAR AS THE SEVERITY OF THE CONVECTION...STILL EXPECT ORDINARY STORMS...WITH A VERY SMALL CHANCE FOR WIND/HAIL ACROSS THE SOUTHERN COUNTIES /NORTHEAST IOWA EXTREME SOUTHWEST WISCONSIN/. REASON BEING...THERE WILL NOT BE ENOUGH INSTABILITY GENERATED FOR IT...ALTHOUGH SHEAR REMAINS FAVORABLE FOR MULTICELLULAR/LINEAR STORM MODE /LINEAR SOUTH...MULTICELLULAR NORTH/. ETA CAPES ARE ERRONEOUS DUE TO ITS EXPECTATION THAT 70+ DEWPOINTS WILL REACH THE FORECAST AREA. THAT IS QUITE OVERDONE. EXPECT BEST CAPES TO BUILD OVER THE SOUTHERN PORTION OF THE FORECAST AREA WITH 55-62 DEGREE DEWPOINTS. THIS WOULD BE THE MOST FAVORABLE AREA FOR WIND/HAIL STORMS THIS AFTERNOON/EVENING. CLOUDS SHOULD BE THE LEAST IN THAT REGION...WITH SOME CHANCE OF AIRMASS RECOVERY FOR CAPE BUILDING. EXPECT CAPES OF 1000-2000 J/KG BY AFTERNOON/EVENING IN THIS REGION. ELSEWHERE...THE CHANCE IF MINIMAL. TONIGHT/TUESDAY IS THE MOST DIFFICULT OF THE FORECAST PERIOD. THE LOW LEVEL JET SHOULD CONTINUE EAST OF THE FORECAST AREA. THIS WOULD...FOR THE MOST PART...PRECLUDE THE FORECAST AREA OF CONVECTION AFTER MIDNIGHT. DO NOT AT ALL LIKE THE WAY THE GFS REDEVELOPS PRECIPITATION OVER THE FORECAST AREA. THERE IS NO FORCING NOTED IN ANY LAYER AND INSTABILITY IS MINIMAL IF NOT ZERO DURING THE SAID TIME PERIOD. LOWERED PRECIPITATION CHANCES. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY STRONG NEGATIVE HEIGHT ANOMALY WILL DEVELOP OVER HUDSON BAY FOR THE WEEKEND. THIS WILL BRING COOLER TEMPERATURES TO THE REGION...KEEPING AVERAGES BELOW NORMA. SEVERAL DISTURBANCES WILL ROTATE AROUND THIS FEATURE...BRINGING A CHANCE OF PRECIPITATION TO THE FORECAST AREA. AT THIS TIME...ASCERTAINING THE TIMING OF THESE MOVING THROUGH THE FORECAST AREA IS UNREALISTIC. && .ARX...WATCHES/WARNING/ADVISORIES... IA...NONE. WI...NONE. MN...NONE. && $$ KRC wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1122 AM EDT MON AUG 16 2004 .DISCUSSION... WV IMAGERY SHOWS A SHORTWAVE PUSHING THRU SOUTHERN MN. PCPN ASSOCIATED WITH THIS WAVE HAS AVOIDED THE U P THUS FAR...KEEPING TO THE SOUTH AND WEST WHERE HIGHER THETA-E AIR RESIDES. MORNING GRB/APX SOUNDINGS SHOW THE EXTENT OF THE DRY AIR IN PLACE. SFC FRONT ITSELF LAGS THE UPPER TROF AND IS WELL TO OUR WEST IN MN...AND SWLY BLYR FLOW ACROSS OUR CWA IS STILL ANTICYCLONIC. CURRENT DEWPTS ARE ONLY IN THE LOWER 50S (UPR 50S NEAR WARM LAKE MICHIGAN)...AND UPSTREAM OBS IN NRN WI SHOW SIMILAR VALUES. THUS PCPN IS HAVING A HARD TIME MAKING IT THIS FAR NE. ETA/RUC CONTINUE TO SHOW SOME INCREASE IN H8 THETA-E ADVECTION AND UPPER DIVERGENCE THIS AFTN AND EVENING AS THE SHORTWAVE TRACKS INTO WI...AND THIS WOULD SEEM TO CONCUR WITH RADAR TRENDS SHOWING PCPN ADVANCING INTO NRN WI. ALTHOUGH DYNAMICS ARE WEAK...THEY SHOULD FOR THE MOST PART BE ENOUGH TO OVERCOME THE DRY AIR AND LACK OF LOW LEVEL CONVERGENCE (THOUGH QPF WILL NOT BE MUCH). BEST CHANCE OF PCPN WILL BE IN THE SOUTHWESTERN U P...AND IN THIS AREA HAVE SUSTAINED SCATTERED POPS THIS AFTN/EVNG. HAVE SCALED BACK WORDING TO ISOLD ON THE KEWEENAW WHERE SUPPORT IS WEAKEST. RIDGE WILL HOLD ON IN THE EAST UNTIL THIS EVENING...SO DRY FCST THIS AFTN FOR LOCATIONS EAST OF MQT-ESC LOOK GOOD. WITH A LACK OF LOW LEVEL MOISTURE...ETA/RUC SBCAPES ARE TOO LOW (LESS THAN 100 J/KG) TO WARRANT MENTIONING TS. PCPN WILL END IN THE WEST OVERNIGHT TONIGHT AND IN THE EAST EARLY TUE AS THE TROF MOVES THROUGH AND MID LEVEL DRYING/H8-H5 Q-VECTOR DIVERGENCE WORKS IN. CURRENT FCST HAS THIS WELL IN HAND. HIGHS FROM MID 60S IN THE SOUTHWEST (WHERE PCPN WILL BEGIN SHORTLY) TO LOWER/MID 70S IN THE CENTRAL AND EAST LOOK GOOD. BLYR WINDS INCREASE TO 15-20KT THIS AFTN...ENOUGH TO OFFSET A LAKE SUPERIOR BREEZE ALTOGETHER...SO WARMEST READINGS SHOULD BE ALONG THE NORTHERN SHORE. HAVE ALREADY TWEAKED TEMP/WX GRIDS. UPDATED ZONES COMING SHORTLY. && .PREVIOUS DISCUSSION... MID LVL DRYING (AIRMASS FM CQYD) CONTINUES E BEHIND DEPARTING MID LVL TROF AXIS TUE MRNG WITH ARRIVAL OF DNVA/DEEP LYR QVECTOR DVGC/ STRENGTHENING MID LVL SUBSIDENCE INVRN. THIS PROCESS IS INTERRUPTED A BIT IN THE GFS FCST WITH ARRIVAL OF WHAT APPEARS TO BE CONVECTIVELY ENHANCED SHRTWV. THIS SYS NOW OVER EXTREME SW CAN...AND PREFER ETA FCST OF THIS SHRTWV MOVING WELL S OF FA AND BEING WEAKER. ETA FCST SDNGS HOWEVER SHOW CONSIDERABLE SBCAPE DVLPG DURING THE DAY UNDER THE MID LVL DRYING/DEPARTING CLDS. MODEL SHOWS CAPES INCRSG TO AS HI AS 1500 J/KG...BUT FCST SFC DWPTS APRCHG 65 SEEM UNREALISTIC. MODIFICATION OF ETA FCST SDNGS FOR SFC DWPT IN THE 55 TO 60 RANGE (AS OBSVD BEHIND TROF THIS MRNG) RESULTS IN CAPES 300-500 J/KG LOWER THAN EXPLICIT MODEL FCST. SINCE ETA DOES NOT GENERATE QPF DURING THE AFTN OVER FA EVEN WITH HI MODEL DVLPD INSTABILITY (GFS DOES GENERATE QPF)...BELIEVE MID LVL DRYING/STABILIZATION WL DOMINATE AND PREVENT SHRA/TSRA. HOWEVER AS DAYSHIFT POINTED OUT...INCRSG INSOLATION THAT CAUSES TMAX TO APRCH HI END OF MOS FCST TEMPS PER DEEP MIXING THRU PBL ON ETA FCST SDNGS/FLAT PRES GRADIENT WL RESULT IN LK BREEZE FORMATION. SINCE MOS FCSTS INDICATE CHC POPS ALMOST EVERYWHERE TUE AFTN...CONFIDENCE NOT HI ENUF TO REMOVE GOING SHRA/TSRA CHCS FM FCST OVER ERN ZNS WHERE POTENTIAL LK BREEZE CNVGC BTWN SUP/MI BNDRYS MIGHT COUNTER NEGATIVE MID LVL PROCESSES THAT DON'T ARRIVE IN FULL FORCE IN THAT PART OF THE CWA UNTIL THE AFTN. SHRA OVER THE ERN CWA WL DSPT QUICKLY LATE TUE AFTN WITH WANING INSOLATION UNDER MID LVL DRYING. TUE NGT SHUD BE ON THE TRANQUIL SIDE WITH DNVA/DEEP QVECTOR DVGC/SUBSIDENCE/ARRIVAL OF WEAK HI PRES RDG. SINCE GFS RETAINS DVLPG WAD/DESTABILIZATION (SSI FALLING AOB ZERO) OVER NW LK SUP TOWARD 12Z WED IN ADVANCE OF POTENT SHRWTV FCST TO ARRIVE NEAR LK WINNIPEG THEN...WL RETAIN LO CHC LATE NGT SHRA/ TSRA OVER THE KEWEENAW PENINSULA/ISLE ROYALE AND ADJOINING LK SUP EVEN THOUGH GFS DOES NOT GENERATE ANY PCPN (UKMET DOES). OTRW...FA WL BE CLR TO PCLDY WITH AN INCRSG SW FLOW RESTRICTING THE DIURNAL DCRS IN TEMP AT LEAST OVER THE NW HALF OF FA. LOWER TMINS AOB MOS GUIDANCE OVER THE INTERIOR SCNTRL/E WHERE PRES GRADIENT DOES NOT TIGHTEN TOO MUCH BEFORE 12Z. GFS/UKMET/ETA IN GOOD AGREEMENT ON DRIVING STRG SFC COLD FNT ACRS THE FA AND INTO NRN LK MI BY 00Z THU (CNDN MODEL A BIT SLOWER) AS POTENT SHRTWV NR LK WINNIPEG AT 12Z WED MOVES ACRS ONTARIO. DESPITE STRENGTH OF FNT AND POTENTIAL FOR CONSIDERABLE HTG OF LLVLS WITH FROPA AT DIURNAL MAX/MSTR CNVGC/ FRONTOGENETIC ENHANCEMENT... ETA SHOWS LINX TO -5C/H85 TEMP RISING NR 16C (UKMET/GFS A BIT MORE CONSERVATIVE WITH 14C)...WL NOT INCRS GOING CHC POPS DUE TO FCST LOCATION OF FA IN RIGHT EXIT OF SUPPORTING H3 JET MAX. GFS/ETA MOS POPS SUPPORT THIS FCST. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION........JKL PREV DISCUSSION...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NORMAN OK 1105 AM CDT MON AUG 16 2004 .UPDATE... WILL MAKE A FEW MORE CHANGES TO POPS FOR THIS AFTERNOON. AFTER U/A ANALYSIS AND LOOK AT 12Z MODELS...WILL BUMP POPS UP A BIT MAINLY OVER THE NORTHERN 1/3RD OF OKLAHOMA...WITH LOW CHANCES ELSEWHERE. THE /THE WHITES OF ITS EYES/ ARE ALREADY SHOWING...AS CONVECTION DEVELOPS JUST NORTH OF OUR CWA NEAR MID-UPPER LEVEL TROUGH AXIS. THIS ACTIVITY EXPECTED TO CONTINUE DEVELOPING AND PERHAPS BECOME MORE WIDEPSREAD AS IT SPREADS TO THE EAST AND SOUTH. 11 && 950 AM .UPDATE... WILL UPDATE PACKAGE TO TWEAK POPS AND SKY COVER BASED ON CURRENT TRENDS. DOUBLE-BARREL PATTERN WITH VORT MAX OVER EAST CENTRAL OKLAHOMA AND SOUTH CENTRAL KANSAS. SOMEWHAT DIFFICULT TO KEEP POPS OUT OF THE WESTERN AND CENTRAL AREAS THIS AFTERNOON AS MAIN MID-UPPER LEVEL TROUGH AXIS MOVES THROUGH. WARM/MOIST AIR ADVECTION CONTINUES FROM SOUTHWEST TO NORTHEAST AHEAD OF THIS FEATURE...EVIDENT BY CONTINUING CLOUDS AND SHOWERS OVER WESTERN NORTH TEXAS. WILL EXPAND AFTERNOON POPS BACK WEST TO INCLUDE CENTRAL OKLAHOMA AND THE RED RIVER VALLEY OF OKLAHOMA AND WESTERN NORTH TEXAS. MAIN COVERAGE OF ANY PRECIP THIS AFTERNOON STILL APPEARS TO BE NEAR/EAST OF WEAK STATIONARY BOUNDARY EXTENDING FROM AROUND ENID AND PONCA CITY...TO JUST EAST OF OKC...TO LAKE TEXOMA. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 87 65 91 68 / 20 10 0 10 HOBART OK 87 66 92 68 / 10 0 0 0 WICHITA FALLS TX 89 67 93 69 / 30 10 0 0 GAGE OK 87 64 91 67 / 20 0 0 20 PONCA CITY OK 85 65 90 68 / 60 20 0 10 DURANT OK 87 66 92 69 / 40 10 0 0 && 11 && 639 AM .UPDATE... LIFT AND DESTABILIZATION ASSOCIATED WITH THE LOW LEVEL JET HAVE FOCUSED THUNDERSTORM DEVELOPMENT A BIT FARTHER NORTH THIS MORNING THAN EXPECTED. MOST ACTIVITY HAS BEEN OVER SOUTH CENTRAL KANSAS AND EXTREME NORTHERN OKLAHOMA...WITH A SECONDARY LESS INTENSE BAND OF SHOWERS EXTENDING INTO SOUTHEAST OKLAHOMA. WITH ONLY WEAK COLD POOLS BEING GENERATED BY THE CONVECTION...AND THE RUC CONTINUING TO FOCUS THE STRONGEST ASCENT AND HIGHEST INSTABILITY OVER SOUTHERN KANSAS... THERE APPEARS TO BE ONLY A SLIM CHANCE OF GENERATING CONVECTION MUCH FARTHER SOUTH. POPS HAVE BEEN REDUCED ACROSS MOST AREAS...WITH HIGHEST POPS CONFINED TO NORTH CENTRAL OKLAHOMA. BY AFTERNOON...AS THE SHORTWAVE TROUGH OVER KANSAS MOVES THROUGH THE AREA...MOST IF NOT ALL CHANCES OF RAIN COULD BE OVER FOR THE DAY. FORECAST UPDATES ARE COMING OUT SHORTLY... JAMES ------------------------- 208 AM CDT MON AUG 16 2004 .DISCUSSION... LIKE THE LAST SEVERAL NIGHTS...SHOWERS AND STORMS WILL RANGE ACROSS NORTHWEST TO SOUTHERN OK BEFORE NOON TODAY SUPPORTED BY THE LOW LEVEL JET IN THE VERY MOIST LOWER LAYERS. HOWEVER...THE UPPER FLOW IS EXPECTED TO PULL NORTH OF OK LATER TODAY AS THE UPPER RIDGE BUILDS MORE EAST INTO CO AND WEST TX BY TONIGHT. THIS IS THE REASON FOR NON POPS IN TUESDAY'S FORECAST. TEMPERATURES MORE LIKE SEASONABLE NORMALS WILL RETURN TUESDAY AND WEDNESDAY BEFORE THE NEXT FRONT INFLUENCES THE SOUTHERN PLAINS LATER IN THE WEEK. THE NEXT CHANCE FOR RAIN IS THURSDAY AND FRIDAY...ALTHOUGH FORECAST FRONTAL POSITION APPEARS PROBLEMATIC BECAUSE OF WEAK WESTERLY FLOW ALOFT. IT MAY TAKE STORMS ON THE FRONT OVER THE CENTRAL PLAINS TO MOVE IT SOUTH OF KS. EVEN SO...IT APPEARS THAT IT SHOULD INFLUENCE MOST OF THE STATE BY THE END OF THE WEEK. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 87 65 91 68 / 40 0 0 10 HOBART OK 87 66 92 68 / 30 0 0 0 WICHITA FALLS TX 89 67 93 69 / 20 0 0 0 GAGE OK 87 64 91 67 / 20 0 0 20 PONCA CITY OK 85 65 90 68 / 40 0 0 10 DURANT OK 87 66 92 69 / 40 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 9 ok AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NORMAN OK 950 AM CDT MON AUG 16 2004 .UPDATE... WILL UPDATE PACKAGE TO TWEAK POPS AND SKY COVER BASED ON CURRENT TRENDS. DOUBLE-BARREL PATTERN WITH VORT MAX OVER EAST CENTRAL OKLAHOMA AND SOUTH CENTRAL KANSAS. SOMEWHAT DIFFICULT TO KEEP POPS OUT OF THE WESTERN AND CENTRAL AREAS THIS AFTERNOON AS MAIN MID-UPPER LEVEL TROUGH AXIS MOVES THROUGH. WARM/MOIST AIR ADVECTION CONTINUES FROM SOUTHWEST TO NORTHEAST AHEAD OF THIS FEATURE...EVIDENT BY CONTINUING CLOUDS AND SHOWERS OVER WESTERN NORTH TEXAS. WILL EXPAND AFTERNOON POPS BACK WEST TO INCLUDE CENTRAL OKLAHOMA AND THE RED RIVER VALLEY OF OKLAHOMA AND WESTERN NORTH TEXAS. MAIN COVERAGE OF ANY PRECIP THIS AFTERNOON STILL APPEARS TO BE NEAR/EAST OF WEAK STATIONARY BOUNDARY EXTENDING FROM AROUND ENID AND PONCA CITY...TO JUST EAST OF OKC...TO LAKE TEXOMA. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 87 65 91 68 / 20 10 0 10 HOBART OK 87 66 92 68 / 10 0 0 0 WICHITA FALLS TX 89 67 93 69 / 30 10 0 0 GAGE OK 87 64 91 67 / 20 0 0 20 PONCA CITY OK 85 65 90 68 / 60 20 0 10 DURANT OK 87 66 92 69 / 40 10 0 0 && 11 && 639 AM .UPDATE... LIFT AND DESTABILIZATION ASSOCIATED WITH THE LOW LEVEL JET HAVE FOCUSED THUNDERSTORM DEVELOPMENT A BIT FARTHER NORTH THIS MORNING THAN EXPECTED. MOST ACTIVITY HAS BEEN OVER SOUTH CENTRAL KANSAS AND EXTREME NORTHERN OKLAHOMA...WITH A SECONDARY LESS INTENSE BAND OF SHOWERS EXTENDING INTO SOUTHEAST OKLAHOMA. WITH ONLY WEAK COLD POOLS BEING GENERATED BY THE CONVECTION...AND THE RUC CONTINUING TO FOCUS THE STRONGEST ASCENT AND HIGHEST INSTABILITY OVER SOUTHERN KANSAS... THERE APPEARS TO BE ONLY A SLIM CHANCE OF GENERATING CONVECTION MUCH FARTHER SOUTH. POPS HAVE BEEN REDUCED ACROSS MOST AREAS...WITH HIGHEST POPS CONFINED TO NORTH CENTRAL OKLAHOMA. BY AFTERNOON...AS THE SHORTWAVE TROUGH OVER KANSAS MOVES THROUGH THE AREA...MOST IF NOT ALL CHANCES OF RAIN COULD BE OVER FOR THE DAY. FORECAST UPDATES ARE COMING OUT SHORTLY... JAMES ------------------------- 208 AM CDT MON AUG 16 2004 .DISCUSSION... LIKE THE LAST SEVERAL NIGHTS...SHOWERS AND STORMS WILL RANGE ACROSS NORTHWEST TO SOUTHERN OK BEFORE NOON TODAY SUPPORTED BY THE LOW LEVEL JET IN THE VERY MOIST LOWER LAYERS. HOWEVER...THE UPPER FLOW IS EXPECTED TO PULL NORTH OF OK LATER TODAY AS THE UPPER RIDGE BUILDS MORE EAST INTO CO AND WEST TX BY TONIGHT. THIS IS THE REASON FOR NON POPS IN TUESDAY'S FORECAST. TEMPERATURES MORE LIKE SEASONABLE NORMALS WILL RETURN TUESDAY AND WEDNESDAY BEFORE THE NEXT FRONT INFLUENCES THE SOUTHERN PLAINS LATER IN THE WEEK. THE NEXT CHANCE FOR RAIN IS THURSDAY AND FRIDAY...ALTHOUGH FORECAST FRONTAL POSITION APPEARS PROBLEMATIC BECAUSE OF WEAK WESTERLY FLOW ALOFT. IT MAY TAKE STORMS ON THE FRONT OVER THE CENTRAL PLAINS TO MOVE IT SOUTH OF KS. EVEN SO...IT APPEARS THAT IT SHOULD INFLUENCE MOST OF THE STATE BY THE END OF THE WEEK. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 87 65 91 68 / 40 0 0 10 HOBART OK 87 66 92 68 / 30 0 0 0 WICHITA FALLS TX 89 67 93 69 / 20 0 0 0 GAGE OK 87 64 91 67 / 20 0 0 20 PONCA CITY OK 85 65 90 68 / 40 0 0 10 DURANT OK 87 66 92 69 / 40 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 9 ok AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NORMAN OK 639 AM CDT MON AUG 16 2004 LIFT AND DESTABILIZATION ASSOCIATED WITH THE LOW LEVEL JET HAVE FOCUSED THUNDERSTORM DEVELOPMENT A BIT FARTHER NORTH THIS MORNING THAN EXPECTED. MOST ACTIVITY HAS BEEN OVER SOUTH CENTRAL KANSAS AND EXTREME NORTHERN OKLAHOMA...WITH A SECONDARY LESS INTENSE BAND OF SHOWERS EXTENDING INTO SOUTHEAST OKLAHOMA. WITH ONLY WEAK COLD POOLS BEING GENERATED BY THE CONVECTION...AND THE RUC CONTINUING TO FOCUS THE STRONGEST ASCENT AND HIGHEST INSTABILITY OVER SOUTHERN KANSAS... THERE APPEARS TO BE ONLY A SLIM CHANCE OF GENERATING CONVECTION MUCH FARTHER SOUTH. POPS HAVE BEEN REDUCED ACROSS MOST AREAS...WITH HIGHEST POPS CONFINED TO NORTH CENTRAL OKLAHOMA. BY AFTERNOON...AS THE SHORTWAVE TROUGH OVER KANSAS MOVES THROUGH THE AREA...MOST IF NOT ALL CHANCES OF RAIN COULD BE OVER FOR THE DAY. FORECAST UPDATES ARE COMING OUT SHORTLY... JAMES ------------------------- 208 AM CDT MON AUG 16 2004 .DISCUSSION... LIKE THE LAST SEVERAL NIGHTS...SHOWERS AND STORMS WILL RANGE ACROSS NORTHWEST TO SOUTHERN OK BEFORE NOON TODAY SUPPORTED BY THE LOW LEVEL JET IN THE VERY MOIST LOWER LAYERS. HOWEVER...THE UPPER FLOW IS EXPECTED TO PULL NORTH OF OK LATER TODAY AS THE UPPER RIDGE BUILDS MORE EAST INTO CO AND WEST TX BY TONIGHT. THIS IS THE REASON FOR NON POPS IN TUESDAY'S FORECAST. TEMPERATURES MORE LIKE SEASONABLE NORMALS WILL RETURN TUESDAY AND WEDNESDAY BEFORE THE NEXT FRONT INFLUENCES THE SOUTHERN PLAINS LATER IN THE WEEK. THE NEXT CHANCE FOR RAIN IS THURSDAY AND FRIDAY...ALTHOUGH FORECAST FRONTAL POSITION APPEARS PROBLEMATIC BECAUSE OF WEAK WESTERLY FLOW ALOFT. IT MAY TAKE STORMS ON THE FRONT OVER THE CENTRAL PLAINS TO MOVE IT SOUTH OF KS. EVEN SO...IT APPEARS THAT IT SHOULD INFLUENCE MOST OF THE STATE BY THE END OF THE WEEK. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 87 65 91 68 / 40 0 0 10 HOBART OK 87 66 92 68 / 30 0 0 0 WICHITA FALLS TX 89 67 93 69 / 20 0 0 0 GAGE OK 87 64 91 67 / 20 0 0 20 PONCA CITY OK 85 65 90 68 / 40 0 0 10 DURANT OK 87 66 92 69 / 40 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 9 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 200 PM MDT MON AUG 16 2004 .SHORT TERM... (TODAY AND TONIGHT) CURRENTLY...WV AND RUC ANALYSIS SHOWING TROF ACROSS WESTERN US COMPOSED OF VIGOROUS SHORTWAVE OVER NEVADA AND SMALLER LOBE OVER SOUTHERN ARIZONA. LIGHTNING BEGINNING TO FIRE UP ALONG LEADING EDGE OF MID/HIGH LEVEL MOISTURE PLUME AHEAD OF THIS TROF...AND ALONG HIGHER TERRAIN. CENTRAL US TROF HAS SLID INTO EASTERN PLAINS...AND BROUGHT NORTHEASTERLY WINDS BEHIND TO NE COLORADO. THIS BOUNDARY IS EXPECTED IN OUR AREA LATER THIS AFTERNOON. FOR TONIGHT...MOISTURE AND INSTABILITY STILL A BIT LIMITED...WITH CAPES RUNNING LESS THAN 1000 J/KG OVER MTNS AND PWS LESS THAN THREE QUARTERS OF AN INCH. HOWEVER TS ARE SLOW MOVERS WITH RIDGE OVERHEAD...SO COULD SEE SOME ISOLD HEAVY RAINFALL. WITH BULK SHEAR RUNNING LESS THAN 20KTS ACROSS AREA...WOULD ANTICIPATE ONLY SEVERE THREAT MAY BE ONE OR TWO PULSE SEVERE STORMS OVER HIGHER TERRAIN. MAY ALSO SEE A FEW STORMS OUT EAST WITH PASSING TROF AND SFC BDRY... CAPES ARE A LITTLE BETTER HERE BUT SHEAR REMAINS LOW. SHOULD NOTE THAT LAPSE RATES OUT WEST AND OVER SAN LUIS VALLEY APPROACH 9.5 C/KM LATER TODAY...WHICH WOULD TYPICALLY SPIN UP DUST DEVILS. COULD SEE SOME LOCAL ENHANCEMENT OF THESE NEAR GROWING TS. UPPED SW MTN POPS TO SCATTERED OVERNIGHT AS MOISTURE AND LIFT STILL MOVING IN. BOTH ETA/AVN BRING ENERGY OVER COLORADO IN THE EARLY TO MID AFTERNOON...PARTICULARLY WESTERN ZONES. MAY SEE AN INITIAL BURST OF CONVECTIVE ACTIVITY AROUND THE NOON HOUR WITH INITIAL VORT PER MESOETA...WITH MANY LIGHTNING STRIKES AND MOST MOISTURE AOA 600 MB MAKING DRY LTG A THREAT. THINK ATMOSPHERE WILL THEN MOISTEN UP RATHER QUICKLY AS PLUME MOVES OVER AND TS COVERAGE INCREASES. WITH THE MOISTURE INCREASE...PLUS NO CRITICAL FUELS...WILL HAVE NO FIRE WEATHER HEADLINES FOR NOW. DECREASED EAST PLAINS POPS TO 10S AS DON'T THINK BEST MSTR AND LIFT WILL BE OVER THEIR AREA BY 0Z. KC .LONG TERM... (WEDNESDAY THROUGH MONDAY) ...MAIN CONCERN DURING THIS PERIOD WILL BE POTENTIAL FOR SOME LOCALLY HEAVY RAINS HIER TRRN...ALONG WITH CLOUDS/PRECIP OVER THE PLAINS... SHORTWAVE WHICH IS CLEARLY INDICATED IN THE WATER VAPOR IMAGERY OVER C NEVADA AS I WRITE WILL BE THE PRIMARY WEATHER MAKER DURING THE EARLY PART OF THIS FORECAST PERIOD. THIS SHORT WAVE IS FORECAST TO GRADUALLY WORK ITS WAY AROUND THE RIDGING OVER THE REGION...COME OVER "THE TOP" AND THEN AFFECT OUR WEATHER. HOW MUCH OF AN EFFECT THIS SYSTEM WILL HAVE ON OUR WX IS THE BIG UNKNOWN. AS THIS IS GOING ON...A MAJOR TROUGH WILL DEVELOP OVER THE CENTRAL PART OF THE COUNTRY...USHERING IN MUCH COLDER WX FOR THE NC PART OF THE CONUS. WEDNESDAY...ABOVE MENTIONED SHORT WAVE WILL BE ASSISTING A COLD FRONT INTO THE REGION. BELIEVE FRONT WILL BE COMING IN A BIT EARLIER THEN MODELS PROG IT...AND HAVE TWEAKED TEMPS DOWN A BIT ON THIS DAY. FAR S PARTS AND INTERIOR VALLEYS WILL NOT FEEL THE EFFECTS OF THIS SYSTEM DURING MOST OF THE DAY AND LEFT THESE AREAS ON THE WARM SIDE. I AM A BIT CONCERNED WITH RATHER IMPRESSIVE FORCING AND LOTS OF MONSOON MOISTURE OVER THE REGION THAT WE MAY SEE SOME HEAVY RAINS OVER THE INTERIOR MTN AREAS...AND FLASH FLOODING OVER THE HIER TRRN MAY BECOME AN ISSUE ON THIS DAY. THIS SITUATION WILL HAVE TO BE MONITORED CLOSELY. WEDNESDAY NIGHT...FRONT WILL HAVE MOVED THROUGH MOST OF PLAINS AND WILL AFFECT HIER TRRN TO A CERTAIN EXTENT...ESPECIALLY C MTN AREAS. DECIDED TO KEEP LOTS OF CLOUD OVER THE REGION ALL NIGHT LONG WITH DEVELOPING UPSLOP AND KEPT SLIGHT CHANCE OF POPS IN FCST. SCT STORMS WILL LIKELY BE ONGOING EVERYWHERE EARLY WED NIGHT BUT SHOULD GRADUALLY TAPER OFF...BUT PRECIP OF SOME EXTENT WILL LIKELY LAST INTO THE NIGHTTIME HOURS. THURSDAY...TWEAKED MAXES DOWN A BIT AND WOULD NOT BE TOO SURPRISED IF LATER SHIFTS TWEAK THEM DOWN SOME MORE. EXPECT LOTS OF CLOUDS THIS DAY ALL AREAS...AND CLOUDS ON THE PLAINS WILL BE SLOW TO CLEAR ON THE PLAINS...IF THEY CLEAR AT ALL. WITH THE DISTURBANCE OVERHEAD AND LOTS OF MOISTURE AROUND...IT COULD BE ON THE DREARY SIDE ON THIS DAY OVER MOST OF THE REGION. IF IT SHOULD NOT BE SO DREARY AND WE GET MORE SUN THAN NOT...THEN THIS COULD BE A RATHER BIG SVR WX DAY AS PRETTY GOOD SHEAR AND STOUT UPPER LVL FORCING WILL BE IN PLACE (AT LEAST ACCORDING TO THE SHORT RANGE GFS). ATTM...I'M LEANING MORE TOWARDS IT BEING TOO STABLE FOR ANY SIGNIF SVR. AS FOR THE REST OF THE FCST...DID NOT MAKE AND SIGNIF CHANGES. OVERALL...MOD TO LIGHT NW FLOW WILL CONTINUE WITH TEMPS REMAINING ON THE SEASONABLE SIDE. WITH NW FLOW...EXPECT CHANCE OF SHOWERS/STORMS EVERY AFTERNOON. SURROUNDING WFO'S...THANKS FOR THE COORD. \/HODANISH && .PUB WATCHES/WARNINGS/ADVISORIES...NONE && $$ co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1215 PM CDT MON AUG 16 2004 .DISCUSSION... UPDATED THE FORECAST TO REMOVE MORNING WORDING. OTHERWISE PARTLY TO MOSTLY SUNNY THIS AFTERNOON AND A BIT WARMER WITH HIGHS IN THE LOWER 80S AND SOUTH WINDS 5 TO 15 MPH. NOON SURFACE ANALYSIS HAS 1027 MB HIGH PRESSURE OVER NW OHIO AND RIDING SW ACROSS THE MID MS VALLEY AND INTO ARKANSAS. 1014 MB LOW PRESSURE WAS OVER SE SD WITH A COLD FRONT OVER CENTRAL NEBRASKA AND NW KS. AREA OF CONVECTION AHEAD OF THIS LOW OVER CENTRAL IOWA WHERE SLIGHT RISK IS TODAY. THIS CONVECTION IS MOVING ESE TOWARD SOUTHERN WI AND NORTHERN IL FROM I-80 NORTH. THIS ASSOCIATED WITH A VIGOROUS UPPER LEVEL TROF OVER THE UPPER MS VALLEY AND MOVING EAST INTO WI THIS AFTERNOON. ANOTHER SMALLER AREA OF CONVECTION WAS OVER SW MO AND DRIFTING SLOWLY EAST. RUC AND ETA KEEPING CENTRAL IL DRY THROUGH 00Z...THEN QPF MOVES INTO NORTHERN COUNTIES THIS EVENING FROM PEORIA NORTH WHILE BETTER CHANCE OF CONVECTION NORTH OF I-80 WHERE BRUNT OF UPPER LEVEL ENERGY PASSES. NOON TEMPS IN THE MID 70S AND SHOULD CLIMB INTO THE LOWER 80S MOST AREAS WITH SSW WINDS 5 TO 15 MPH AND STRONGEST NW OF THE IL RIVER WHERE PRESSURE GRADIENT A BIT TIGHTER. DEWPOINTS ARE STILL LOW TODAY WITH UPPER 40S TO MIDDLE 50S. .PREV DISCUSSION... PROBLEM AREA TODAY IS THE TWO FRONTAL SYSTEMS TO MOVE INTO CWA...STRETCH OUT EAST-WEST...STALL AND WASH OUT THIS WEEK. THE RESULT WILL BE CONTINUED CHANCE OF PRECIPITATION THROUGH MUCH OF THE WEEK. THERE IS VERY LITTLE SIGNIFICANT DIFFERENCES BETWEEN MODELS. GFS MAY BE A LITTLE BIT BETTER ON FRONTAL SYSTEM MOVEMENT AND A BIT SLOWER ON THE START OF PRECIPITATION. SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT... MOISTURE CHANNEL SATELLITE IMAGERY SHOWS UPPER LEVE VORT MAX IN NROTHEASTERN SD AND MOVING EAST SOUTHEAST. BOTH MODELS SIMILAR IN DEPICTION OF VORT PATTERN WITH THIS SYSTEM AS IT TRACKS TOWARD LOWER GREAT LAKES AND WEAKENS. IT WILL DRAG FRONTAL SYSTEM WITH IT INTO CWA ON TUESDAY...BUT THE FRONTAL IS EXPECTED TO WEAKEN AND WASH OUT IN OUR REGION. 00Z UPPER AIR AND SURFACE DATA THIS EVENING SHOWS MOISTURE RETURN ALREADY OCCURRING NORTHWARD INTO THE PLAINS REGION...HOWEVER DUE TO THE SLOW HIGH PRESSURE RIDGE MOVEMENT...THE MOISTURE RETURN HAS BEEN LIMITED SO FAR FOR MS VALLEY AREA. LIGHT SOUTHERN WINDS TODAY THOUGH SHOULD ALLOW SOME MOIST AIR TO MOVE BACK INTO AREA TODAY AND TONIGHT...BUT WITH THE SPEED OF FRONT STILL LIKE THE CURRENT FORECAST TIMING OF THE PRECIPITATION FOR TONIGHT AND THEN MAINLY ON TUESDAY. WILL THEREFORE NOT CHANGE ANY OF THE CURRENT TIMING ON BRINGING IN THE PRECIPITATION. THOUGH FIRST FRONT WASHES OUT OVER AREA TUESDAY NIGHT...LINGERING MOISTURE SHOULD BE ENOUGH FOR CHANCE POPS WEDNESDAY AND WEDNESDAY NIGHT BEFORE THE SECOND FRONT REACHES AREA. IF THERE IS A POSSIBLE "BREAK" IN THE PRECIPTATION CHANCES...IT WOULD BE ON WEDNESDAY TO WEDNESDAY NIGHT BETWEEN THE TWO FRONTS. HOWEVER WITH PRECIPITATION ALREADY IN THE FORECAST WILL CONTINUE CONTINUITY TIL BETTER SYSTEM TIMING CAN BE SEEN. LONG TERM...THURSDAY THROUGH SUNDAY... SECOND FRONT ON TODAY'S MODEL RUN APPEARS TO BE WEAKER THAN PREVIOUS RUN WITH NOT AS SIGNIFICANT A SURFACE HIGH BEHIND IT. MODELS STILL CONTINUE TREND OF DEVELOPING UPPER LEVEL LOW CENTER VORTEX IN CANADA. MINOR WAVES ROTATING AROUND UPPER SYSTEM ARE SHOWN TRIGGERING WAVE ON STALLED FRONT...AND MOVING OVER MIDWEST. WILL KEEP THE CURRENT FORECAST OF CHANCE POPS TIL SATURDAY. NEW 00Z GFSLR MODEL RUN A LITTLE DIFFERENT THAN PREVIOUS RUNS...AS HUDSON BAY VORTEX PROGGED TO ROTATE ANOTHER FRONTAL SYSTEM INTO AREA ON SATURDAY INTO SUNDAY. COORDINATION WITH SURROUNDING OFFICES LED US TO LEAVE CURRENT DRY FORECAST FOR NOW...BUT THIS WILL NEED TO BE WATCHED LATER. && .ILX WATCHES/WARNINGS/ADVISORIES... IL...NONE. && $$ HUETTL/GOETSCH il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 327 PM CDT MON AUG 16 2004 .DISCUSSION... SCNDRY S/W VSB IN WV IMAGERY IS ANTICIPATED TO COME INTO PLAY FM THE 4-7PM TIME FRAME ALG THE FNT MOVING INTO THE NWRN CRNR ATTM. PROFILERS ARE NOT SHOWING MUCH WIND HOWEVER FOR ANY SGFNT FNTL CONVERGENCE...BUT THE WAVE SHOULD BE ENOUGH TO RELEASE THE INSTABILITY OF 1-2K J/KG. NW WNDS ALF ARND THE DEEP UPR CYC OVR CANADA SHOULD PROVIDE ENOUGH SHEAR FOR A FEW STORMS TO ROTATE. THE 13KM RUC REMAINS EMPHATIC ABT PCPN MOVS EWD ACRS THE CWA OVRNGT...AND NOT MUCH TMR. KEPT CONTINUITY GOING WITH SML CHCS IN THE SE. BNDRY GOING STNRY IN NRN MO TMR EVENING AHD ANOTHER S/W IN THE WNW FLOW. THE GFS IS MORE INDUSTRIOUS WITH THIS WAVE WHEREAS THE ETA/S ARE NOT AS MUCH. CUR FCSTS HAVE CHC POPS ACRS THE S AND WE WILL CONTINUE THAT THINKING...FIGURING THE FNT WL NOT MOVE NWD MUCH IN SUCH A FLOW PTRN. NXT SGFNT FNT ARRIVES LTR THIS WEEK WITH A FRESH AMS...WITH ANY PCPN THREAT SMALL THROUGH THE WKEND ATTM. TMPS WL APPROACH NORMAL OVER THE NXT COUPLE OF DAYS WITH A FALLBACK AGN LATE IN THE WEEK. LOOKING LIKE AUGUST WILL INDEED BE BELOW IF NOT WELL BELOW NORMAL FOR TMPS. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ MYERS ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 420 PM EDT MON AUG 16 2004 .DISCUSSION... MAIN FCST CONCERNS ARE PCPN CHANCES TONIGHT/TUE AND THEN TIMING FRONT AND SHRA INTO THE AREA WED. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW PERSISTENT STRONG RIDGE OVER WRN NAMERICA WITH 5H HEIGHTS UP TO 585DM OVER ALASKA WHILE DOWNSTREAM TROF COVERS ERN NAMERICA. RECENT RESTRENGTHENING OF WRN RIDGE HAS SENT A COUPLE OF STRONG SHORTWAVES INTO NRN CANADA WHICH ARE ON THEIR WAY TO FORMING LONG ADVERTISED DEEP POLAR VORTEX VCNTY OF HUDSON BAY. CLOSER TO HOME...A SHORTWAVE WAS MOVING THRU WI THIS AFTN WITH BULK OF PCPN STAYING CLOSER TO BETTER FORCING OVER WI. NONETHELESS...THERE IS FAIRLY DECENT COVERAGE OF -SHRA OVER SW UPPER MI THIS AFTN...BUT NO TSRA. AT THE SFC...WEAK SFC TROF IS STILL HANGING BACK OVER MN...AND SOME SHRA/TSRA HAVE DEVELOPED ALONG IT RECENTLY. TO THE NW OF SFC TROF...A FEW SHRA HAVE DEVELOPED AS WELL...SUGGESTING SOME POTENTIAL FOR SHRA HERE TUE. MODELS ARE OVERALL IN GOOD AGREEMENT THRU WED. ETA CONTINUES TO BE FASTER WITH FROPA ON WED...BUT TIMING IS VERY CLOSE NOW TO THE MUCH MORE CONSISTENT AND SLOWER GFS. IN THE SHORT TERM...SHORTWAVE OVER WI HEADS TO LWR MI TONIGHT. WILL BASICALLY USE TRENDS OF PCPN COVERAGE/MOVEMENT THIS AFTN FOR FCST TONIGHT. WILL TREND POPS FROM LOWEST N TO HIGHEST S. IN GENERAL...EXPECT A SLOW DIMINISHING TREND ON PCPN COVERAGE AS SHORTWAVE WEAKENS DUE TO FLOW BECOMING MORE CONFLUENT WITH TIME. WILL TIME END OF PCPN ROUGHLY WITH PASSAGE OF WEAK SFC TROF WHICH MODELS SHOW EXITING ERN FCST AREA SOMETIME TUE MORNING. WEAK PRES GRADIENT IN THE WAKE OF SFC TROF WILL ALLOW DEVELOPMENT OF LAKE BREEZES TUE...AND THE LIGHT WRLY FLOW WILL FAVOR ENHANCED CONVERGENCE OVER ERN FCST AREA AS LAKE BREEZES FROM SUPERIOR AND MICHIGAN HEAD INLAND. SO QUESTION IS POTENTIAL FOR AFTN CONVECTION TO FIRE NEAR BOUNDARIES. 12Z ETA IS A LITTLE SLOWER TO DEVELOP SUBSIDENCE INVERSION SUFFICIENT TO CAP CONVECTION OVER THE E. AT THE SFC...ETA DWPTS IN THE LOW 60S DON'T LOOK TOO BAD GIVEN UPSTREAM DWPTS AND POTENTIAL FOR DWPTS TO RISE A BIT WITH LAKE BREEZE OFF LAKE MICHIGAN. ETA/GFS MOS DWPTS ARE ALSO IN THE 60-63F RANGE. SO...MODIFIED ETA FCST SOUNDING FOR SFC T/TD OF 73/61F NEAR KERY AT 18Z YIELDS CAPE OF ABOUT 1000J/KG. K INDEX IS IN THE 25-30 RANGE. CERTAINLY ENOUGH POTENTIAL TO MAINTAIN AFTN TSRA CHC FROM ALGER/DELTA/MENOMINEE EWD. FARTHER W...HAVE SOME CONCERN THAT A COUPLE OF SHRA/TSRA MIGHT ALSO DEVELOP THERE. ETA FCST SOUNDING SW OF MICHIGAMME WITH SFC T/TD OF 72/56F IS SUFFICIENT TO EXCEED MID LEVEL CAP. FOR NOW...WILL INTRO ISOLD AFTN SHRA/TSRA AS FAR W AS BARAGA/IRON COUNTIES SINCE INLAND AREAS THERE MORE LIKELY TO WARM THE MOST WHILE SOME SFC CONVERGENCE WILL DEVELOP CLOSER TO LAKE SUPERIOR. EXPECT ENOUGH MARINE INFLUENCE OVER WRN COUNTIES WITH WRLY FLOW OFF LAKE TO PREVENT ANY CONVECTION THERE. A GENERALLY QUIET NIGHT EXPECTED TUE NIGHT. SW FLOW BEGINS TO PICK UP LATE (ESPECIALLY W) AHEAD OF SHARP COLD FRONT QUICKLY DROPPING SE THRU SCNTRL CANADA TOWARD UPPER MISSISSIPPI VALLEY. THOUGH POTENTIAL LOOKS MINIMAL BEFORE SUNRISE...HAVE MAINTAINED MENTION OF SHRA/TSRA LATE TUE NIGHT FROM KEWEENAW W AND N DUE TO PROXIMITY OF LOW-LEVEL JET/850MB THETA RIDGE AND ARRIVAL OF WEAK DEEP LAYER QVECTOR CONVERGENCE. SHARP COLD FRONT MOVES ACROSS UPPER MI WED WITH PASSAGE COINCIDENT WITH PEAK HEATING CNTRL/E. SHARP LOW-LEVEL CONVERGENCE NEAR FRONT BUT FAIRLY WEAK DEEP LAYER FORCING AND UNFAVORABLE RIGHT EXIT REGION OF JET OVERHEAD SUGGESTS ONLY A NARROW BAND OF SHRA/TSRA WILL OCCUR WITH FRONT. LIKELIHOOD OF PCPN LOOKS PRETTY GOOD THOUGH GIVEN TIMING OF FROPA AND LOW-LEVEL FORCING. WILL UP POPS TO LIKELY CNTRL/E DUE TO FROPA COINCIDENT WITH PEAK HEATING. AS FOR SVR POTENTIAL...DEEP LAYER SHEAR OF 40-50 KT PER ETA/GFS WILL SUPPORT ORGANIZED CONVECTION AND POSSIBILITY OF SVR STORMS...ESPECIALLY GIVEN TIME OF DAY. STILL LOOKS LIKE A WARM DAY AHEAD OF FRONT AS 850MB TEMPS SURGE TO AROUND 14C WITH ARRIVAL OF THERMAL RIDGE. SW FLOW AND DECENT DISPLAY OF SUNSHINE AHEAD OF FRONT ARGUES FOR TEMPS NEARING 80 CNTRL AND E AWAY FROM LAKE MICHIGAN. HAVE TRIED TO SHOW FALLING TEMPS IN THE GRIDS BEHIND FRONT FROM W TO E DURING THE AFTN. SHOULD BE BREEZY WITH DEEP MIXING AND LOW-LEVEL JET ARRIVING. PCPN WILL END QUICKLY WITH PASSAGE OF FRONT...AND WILL ONLY CARRY EVENING CHC OVER SE/E COUNTIES. 850MB TEMPS PLUMMET TO NEAR 0C BY 06Z THU...BUT WITH SHARP DRYING AND HEALTHY SUBSIDENCE WED NIGHT...NOT EXPECTING MUCH IN THE WAY OF LAKE EFFECT CLOUDINESS OFF SUPERIOR AND CERTAINLY NOT ANY LAKE EFFECT SHRA. SKIES SHOULD BECOME PARTLY CLOUDY EARLY BEHIND FRONT. THU LEADING INTO START OF EXTENDED PERIOD HAS BEEN COMPLICATED BY 12Z MODEL RUNS WHICH ARE MUCH FASTER WITH NEXT SHORTWAVE ROTATING AROUND POLAR VORTEX. HAVE GONE WITH A COMPROMISE TIMING BTWN LATEST RUNS AND EARLIER RUNS WITH NEXT FROPA EARLY FRI. FRI-MON...GFS/ECMWF/CANADIAN/UKMET ARE IN DECENT AGREEMENT PERTAINING TO WEATHER IN THE UPPER GREAT LAKES REGION. FLOW WILL BE DOMINATED BY DEEP POLAR VORTEX VCNTY OF HUDSON BAY EARLY ON. BY THE END OF THIS PERIOD...VORTEX WILL BEGIN TO WEAKEN AND LIFT NE...BUT TROFFING WILL STILL EXTEND S INTO THE AREA. OVERALL...LITTLE CHANGE WILL BE REQUIRED TO GOING FCST FOR FRI-SUN. THERE ARE STILL INDICATIONS OF A SHORTWAVE ROTATING THRU THE AREA IN THE THU NIGHT TO FRI NIGHT TIME FRAME TO PROVIDE A CHC OF SHRA. WILL MAINTAIN DRY FCST FOR SAT/SUN AS HIGH PRES BUILDS INTO THE AREA. 00Z AND ESPECIALLY 06Z/12Z GFS SUGGEST A SHORTWAVE DIGGING INTO THE NRN PLAINS SUN/MON AND THEN MOVING INTO THE WRN LAKES LATER MON. HAVE LITTLE CONFIDENCE IN THIS LATEST TREND AND WILL LEAVE MON DRY FOR NOW. TEMPS WILL BE BLO NORMAL THRU THE PERIOD WITH SOME MODERATION EXPECTED SUN/MON AS VORTEX TO THE N BEGINS TO LIFT NE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 315 PM CDT MON AUG 16 2004 .DISCUSSION... THE RUC MODELS SHOWS CONTINUED LOW LEVEL THETA E ADVECTION ACROSS SOUTH CENTRAL MINNESOTA INTO PORTIONS OF WEST CENTRAL WISCONSIN LATE THIS AFTERNOON AND EARLY EVENING. A WEAK THETA E RIDGE IS ALSO INDICATED IN THE RUC MODEL JUST NORTH OF OUR MINNESOTA FORECAST AREA...NEAR THE DEVELOPING CONVECTION NOW APPROACHING CASS COUNTY. WILL KEEP A CHANCE OF SHOWERS AND THUNDERSTORMS FOR MOST OF OUR FORECAST AREA THIS EVENING DUE TO THESE THETA E FEATURES. THE SOUTH DAKOTA SURFACE LOW PRESSURE CENTER HAS BEEN MOVING SOUTH THIS AFTERNOON AND THERE HAS BEEN LITTLE PUSH BEHIND COLD FRONT ACROSS MINNESOTA. THIS COLD FRONT IS EXPECTED TO STALL ACROSS EAST CENTRAL MINNESOTA LATE TONIGHT. LIGHT WINDS AND RESIDUAL LOW LEVEL MOISTURE EXPECTED TO CREATE CONDITIONS FAVORABLE FOR FOG EAST OF A LINE FROM STAPLES TO WILLMAR. EXPECT FAIR WEATHER TUESDAY WITH DIURNAL CUMULUS. ANOTHER IN A SERIES OF COLD FRONTS WITH THE NORTHWEST FLOW ALOFT IS EXPECTED TO MOVE OVER OUR COUNTY WARNING AREA WEDNESDAY. BEST UPPER LEVEL DYNAMICS ARE FORECAST BY THE GFS MODEL TO SWING ACROSS THE NORTHERN PORTIONS OF OUR COUNTY WARNING AREA WHILE BEST INSTABILITY DEVELOPS ACROSS THE SOUTH. WILL BROAD BRUSH A CHANCE OF CONVECTION WITH THE PASSAGE OF THIS FRONT. LONGER TERM...THURSDAY NIGHT THROUGH MONDAY COOL NW FLOW PATTERN TO CONTINUE UNTIL PERHAPS END OF PERIOD WHEN GFS HINTS AT MORE OF A ZONAL FLOW DEVELOPING. MAIN FORECAST ISSUE WILL BE THE TIMING OF RAPID COOL FRONTS WHICH WILL MOVE THROUGH THE AREA. TREND ON THE SYSTEM FOR THURSDAY NIGHT/FRIDAY IS FOR A FASTER SYSTEM...NOW PROGGED BY GFS TO ALREADY BE SOUTH OF AREA BY 12Z FRI. PERIOD. TEMPERATURES TO REMAIN BELOW SEASONAL NORMS THRU THE PERIOD. && MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn